Wry Heat

Of all the mammals in the desert, the kangaroo rat is perhaps the best adapted to arid conditions: it never needs to drink, nor eat fresh vegetation; it can metabolize water directly from dry seeds.

The diet is almost exclusively seeds, and it prefers seeds high in carbohydrates rather than seeds high in fat or protein. That’s because metabolizing fatty seeds produces heat, and metabolizing protein-rich seeds requires more water to get rid of nitrogen-rich waste products.

The K-rat stores seeds in its burrow where they absorb any humidity, thereby giving the rat some extra moisture. The K-rat has no sweat glands through which to lose water.

The kangaroo rat minimizes moisture loss during respiration with its specialized nasal passages which function as counter-flow heat exchangers. These passages warm the air during inhalation, then cool the air and extract moisture during exhalation.

The kangaroo rat can conserve water by producing urine about 5 times more concentrated than human urine. The rat also produces very dry feces pellets with about one-fifth the water content of a white lab-rat’s pellets.

The kangaroo rat is 4- to 5 inches long with a tail up to 10 inches long. It prefers to hop on its hind legs. It can jump 10 feet and change direction immediately upon landing, something that helps it avoid nocturnal predators.

Although the rat has tiny external ears, the middle ear chamber is highly developed and may be bigger than the braincase itself. This allows the rat to hear low intensity and low frequency sounds such as an owl flying or a rattlesnake ready to strike. This, together with its ability to jump 10 feet, helps it avoid predators.

Mice will eat just about anything, but most prefer plant parts. The grasshopper mouse, however, is a ferocious carnivore. It eats grasshoppers, beetles, spiders, centipedes, millipedes, worms, lizards, scorpions, snakes, and other mice. It hunts like a cat and defends its territory by howling – it is the mouse that roars.

There are several species and most inhabit the grasslands of the great plains, but at least one species is a desert dweller. The Northern Grasshopper mouse has a range from Canada to Mexico, and California to Minnesota; the Southern Grasshopper mouse has a range that includes parts of Nevada, Arizona, New Mexico, and Texas. The southern species is gray-brown- to cinnamon colored with a short white-stripped tail. Most grasshopper mice are relatively stout compared to other mice. The head and body is 3.5″- to 5″ and the tail is 1″ to 2.5″ long.

Usually a male-female pair live together and defend a territory. It marks the territory with musk.

Grasshopper mice have very strong jaw musculature required for killing prey. And they learn quickly how to deal with various prey. One observer describes how the mouse dealt with a 3-inch scorpion in Arizona: ” The mouse would first nip the tail so that the stinger was ineffective. It would then stand the scorpion on end, holding it with its front paws, and methodically eat the writhing creature head first.”

The grasshopper mouse is a nocturnal hunter, a good climber, and active year round. In some areas, scorpions account for almost their entire diet, which might be surprising because the mice are not known to have any immunity to scorpion venom.

These mice will eat seeds, grasses, and grains, and cache them, like other mice, but about 90% of their diet is animal matter. The strangest part of their diet is sand. Biologists think the mice eat sand to aid in digestion, just like some birds ingest gravel. And that’s not all that is strange about their digestive system. As described in an article by Mary Ingle: “A pouch attached to the underside of the stomach opens into it via an aperture too small for large food particles to pass through. The pouch contains all of the gastric glands that contribute to the breakdown of food and are normally found in the stomach of other mammals.” Ingle speculates that the pouch exists because the insect diet would be too rough and damaging for delicate gastric glands to function normally.

The grasshopper mouse digs four kinds of burrows: nesting, retreat/sleeping, caching, and the bathroom.

The mice have several vocalizations. You may have heard their territorial proclamation and mistaken the high-frequency sound for that of an insect. So now, when you are out at night, listen for the mouse that roars.

For a video of a battle between a grasshopper mouse and a very large centipede check here: http://tinyurl.com/ylyme9w Note that centipedes are venomous.

Hummingbirds are ferocious. The males jealously guard feeders and flowers. Females guard nesting sites. I’ve seen one male literally drive another into the ground and jab him with his sharp beak. They have a variety of vocalizations including a “war cry,” a buzzing to warn others away. The Rufous is particularly pugnacious.

For two years, I was involved with the hummingbird reconciliation project run by the University of Arizona. My job was to identify hummers, observe and record their behavior at the feeders in my yard. Over that time I was able to recognize individual birds of the same species, since each has a slight variation from the ideal pictured in a bird book. (And there are fertile hybrids between Anna’s and Costa’s just to make things interesting.) Hummers have good memories. They can return to a feeder year after year.

Hummingbirds live on the edge. Their small size and ability to fly forwards, backwards, upside down, and hover, requires a racing metabolism. At rest, their hearts beat 500 times per minute and this increases to over 1,200 beats per minute during flight. Their wings beat 80 times per second; body temperature is 105- to 109 degrees F.

To function, a hummingbird must consume 70% of its body weight in solid food per day (8-12 calories) and 4- to 8 times its body weight in water. They consume flower nectar (and sugar water), insects, and spiders, as well as tree sap in some areas. They can completely digest sucrose within 20 minutes. According to the Peterson Field Guide, “Despite the predominance of certain hues in hummingbird pollinated flowers, color is far less important… than the quantity and quality of the nectar. When presented with a variety of flowers, hummingbirds will maximize their energy intake by selecting for highest nectar output and richest concentration of sugars, regardless of flower shape or color. Taste also ranks above flower color…” Hummers prefer sucrose over other sugars such as glucose and fructose.

To take in the oxygen they need to burn food, hummers respire at the rate of 300 breaths per minute, even at rest. An excited hummer can breathe twice as fast. Hummers, which are the smallest warm-blooded vertebrates, have the largest heart-to-body ratio of any warm-blooded vertebrate, and the largest brain-to-body ratio of any bird.

They need that relatively big brain for their split-second aerial maneuvering. Hummers are the only birds that gain lift from both the downstroke and up stroke of their wings. The wing motion describes a horizontal figure eight. After the downstroke, the wing is turned over at the shoulder so that the up stroke becomes another downstroke.

There are over 300 species, all in the western hemisphere, and they range from the tip of South America to Alaska. There are 17 species native to the Sonoran Desert Region. Hummers in our region range in length from 2.75 inches to 5.25 inches and weigh 2 to 10 grams (0.07 to 0.35 ounces). Only one hummingbird, the ruby throat, occurs east of the Mississippi River in the U.S.

Most hummers in our region exhibit some migratory behavior. The champion is the Rufous which travels from Mexico to Alaska and back every year. Second is the Ruby Throat which migrates from the eastern U.S. to Mexico. Some travel along the coast, but others take a 13-hour, non-stop flight across the Gulf of Mexico. Those long-distance flyers try to double their body weight for fuel before the trip. Normal flight speed is 25- to 30 mph, but they can do bursts of 60 mph if necessary.

Hummingbirds are very territorial; both sexes protect feeding territories; males protect courtship territories; and females protect nesting territories. Hummers are promiscuous breeders. The male merely courts and mates with receptive females. The female may mate with several males, but she alone builds the nest, lays and incubates the eggs, and tends the young.

The nest is about two inches in diameter. The female uses plant fiber and moss bound with spider web silk. The nest may be lined with hair or feathers and decorated with leaves, bark strips, or lichens to help camouflage it. Generally, two raisin-sized eggs are laid and incubated for about two weeks. Young fledge in about three weeks after hatching.

Hummingbirds are colorful. Most of that color is not produced by pigments as in other birds, but by refraction of light by the feathers. The feathers contain filmy layers that hold granules of melanin and air bubbles, which refract light differently depending on the angle of impingement. The bubbles act as tiny prisms, breaking the light into its component colors.

Where do they go at night, especially in the winter? Hummers are often perilously close to the limits of their energy reserves. On cold nights, when the costs of keeping warm are especially high, it may be too risky for a hummer to maintain its high metabolism. In that case, it will seek shelter of a branch or crevasse, bristle its feathers to let body heat escape, and allow its body temperature to approach that of its surroundings. Its heart rate drops dramatically, and it may stop breathing for minutes at a time. It appears lifeless, clinging motionlessly to its branch with its head drawn close to its body and its bill pointing sharply upward. At daybreak it revs its metabolism and warms itself again. This temporary hibernation is called torpor. Hummingbirds become torpid not only to deal with fuel crises, but also to save energy for migration. And since birds lose moisture with every breath, becoming torpid also helps desert hummers conserve water.

Like many animals in the wild, most hummers don’t survive the first year, but those that do have a life expectancy of three to four years. Some tagged birds in Colorado are known to be 12 years old. One hummer at the Desert Museum was claimed to be 18 years old at death.

If you set up feeders, use 1 part sugar in 4 parts water in the winter, and 1 part sugar in 5 parts water in the summer. Clean the feeders before each filling. Do not use coloring, honey, or artificial sweeteners.

If you want to learn to identify hummingbirds, I recommend “Hummingbirds of North America” a Peterson Field Guide by Sheri L. Williamson. This book contains photos rather than drawings. Photos include close-ups of heads and tails which aid identification. The book also has a good discussion of natural history and good range maps. It covers 31 species. With practice, you can even learn to identify some hummers by their vocalizations. Some species (usually only the males) also have distinctive “hum” of the wing beats.

The Desert Tarantula, Aphonpelma chalcodes, is the most common tarantula seen in the Tucson area and is one of 30 species found in Arizona. Now, during the monsoon, and into early fall is the time to see them. If you notice holes in your yard about the size of a quarter, it is probably a tarantula hole. You can go out at night with a flashlight and observe the females near their holes. Males are more likely to be seen trekking to find females.

Tarantulas are primitive spiders that evolved almost 350 million years ago and have changed little since. The female Desert Tarantula is usually tan or brownish, while the male is darker, usually with black or dark legs and a reddish abdomen. Females have a large abdomen, bigger than the cephalothorax(upper body), while the males have a small abdomen.

Tarantulas dig burrows about 6 inches deep and up to 8 inches laterally, enlarging them as the spider grows. The spiders molt 3- to 6 times a year as they grow, and they can regenerate lost legs upon molting.

Tarantulas are venomous like all spiders, but they are very docile and bite only under extreme provocation. I have picked up many tarantulas and never have been bitten. The venom is usually not harmful to humans. But tarantulas have another defense. Some of the hairs on their abdomen are barbed (urticating hairs) and are very irritating. The tarantula uses its hind legs to flick these hairs at an attacker.

 Tarantulas are long lived spiders. They reach sexual maturity at 8- to 12-years old. Females can live up to 25 years, but the males live only one season beyond sexual maturity. Mating takes place in the summer and fall, and the female stores the sperm until the next spring. The female spins a thick layer of silk in her burrow and in concealed places near the burrow to hold up to 300 eggs. Ants are the main predators of the eggs. The spiderlings hatch in about three weeks and stay in the silk cocoon for another 7 weeks while they grow. The survivors disperse and make their own burrows.

When active, tarantulas may set out strands of silk, “trip wires” around their burrow as a signal that a meal is passing by. They don’t like water, and flee if the burrow gets wet. Sometimes a silk cap on the burrow helps keep water out. Tarantulas do need to drink, but can go up to 90 days without water. During the winter, tarantulas become dormant. They plug their holes with silk and soil, and wait for summer.

And now for a gruesome tale. The Pepsis wasp, Pepsis formosa, is a large (up to 2 inches), bluish-black wasp with orange wings. It is also know as the tarantula hawk. It is a parasite on tarantulas and uses the spiders in its reproductive cycle.

The Pepsis wasp will approach a tarantula and cause the spider to rear its legs, thus exposing its abdomen. The wasp will sting the spider to paralyze it. The wasp will lay an egg on the paralyzed spider and drag it to a hole, bury it, and cover up the hole. When the wasp egg hatches, the larvae eats the flesh of the living tarantula for about 35 days, then spins a cocoon and pupates over the winter. If the wasp egg fails to hatch, the spider can recover. These large wasps generally don’t bother humans.

Tarantulas may look scary, but they are very gentle creatures. You need not be aftraid.

Generally NO. Moisture within the pulp of a cactus is very acidic and many cacti contain toxic alkaloids. You can, however, eat the fruit.

The moisture is acidic because of the way many succulents, including cacti, carry on photosynthesis, the process by which carbon dioxide and water are turned into carbohydrates.

Most plants have their pores (stomates) open during the day to take in carbon dioxide, and use sunlight as a catalyst for the reaction: Carbon dioxide + water sugar + oxygen. But in the desert, plants with pores open during the hot days, lose much water through evapotranspiration.

So, succulents use a modified version of photosynthesis called CAM (Crassulacean Acid Metabolism). CAM plants open their stomates only at night when it is cooler so there is less evapotranspiration. Because there is no sunlight to act as a catalyst, carbon dioxide is stored as an organic acid, principally Malic Acid (C₄H₆O₅). Carbon dioxide is gradually released from the acid during the next day. CAM plants use about one-tenth the water to produce each unit of carbohydrate compared to standard photosynthesis. The price: a much slower growth rate.

Many plants contain malic acid, but usually in lesser quantities than found in cacti. Also cooking generally destroys the acid.

Besides malic acid, succulents produce Oxalic Acid (C₂H₂O₄), which is toxic, as another product of photosynthesis. “Its chief function seems to be sequestering metals, principally calcium. Calcium oxalates often occur as crystalline minerals within the cactus pulp. Their function seems to be aiding structural integrity and enzymatic processes. In fact two crystalline calcium oxalate minerals have been identified in all cacti tested: CaC₂O₄.2H₂O (weddellite) and CaC₂O₄.H₂O (whewellite).” [Source: Plant Physiology, February 2002, Vol. 128, pp. 707-713.] Oxalates are also formed with heavy metals such as copper, perhaps to reduce toxicity to the plant.

Oxalic acid is toxic to humans because it combines with calcium in our bodies to produce calcium oxalates which clog up our kidneys.

So, what about the barrel cactus. Can’t we get water from those? Did you bring along a machete and solar still?

The Seri Indians sometimes used the Fishhook barrel (Ferocactus wislizeni) for emergency water. However, drinking the juice on an empty stomach often caused diarrhea, and some Seri report pain in their bones if they walk a long distance after drinking the juice. The Seri called the Coville barrel (Ferocactus emoryi), “barrel that kills” because eating the flesh of the cactus causes nausea, diarrhea, and temporary paralysis. Think you can tell the two apart? (See: Edible Desert Plants – Barrel Cactus Fruit).

What about Prickly Pear pads we sometimes see in grocery stories or on the menu of Mexican restaurants? What you see are generally young spring pads which naturally contain less oxalic acid. Cooking leaches out the acid. In an emergency you can eat the young pads raw. And there are some spineless cultivars that naturally contain little oxalic acid which can also be eaten raw. These were developed mainly as cattle feed.

The bottom line is you really cannot get a drink from a cactus in spite of what you may have seen in old cowboy movies.

The Arizona-Sonoran Desert region has more wild edible plants than anywhere else on the planet according to ethnobotanists. We have cactus fruit, beans from mesquites and palo verde trees, yuccas, agaves, and nut trees, to name just a few edible plants.

Today, I will focus on the barrel cactus. Most cacti bloom in the spring. The barrel cacti bloom and set fruit in the summer. All cactus fruit is edible, none are poisonous, but not all are palatable. The best cactus tasting fruit comes from the saguaro, prickly pear, and barrel cactus.

There are six species of barrel cactus in the region. The most common in the Tucson area are Ferocactus wislizeni, the Fishhook barrel, and Ferocactus emoryi, Coville barrel. The Fishhook commonly grows 2- to 4 feet high, but some can reach 10 feet. Coville is generally 1- to 4 feet. The flower color of Coville is bright red; the Fishhook flower is usually orange, but can also be yellow or red.

The spines of the Fishhook are strongly-hooked and surrounded by several radial spines. The main central spine of the Coville is usually red, flattened and hooked. The few radial spines are relatively wide.

The fruit starts out green, but gradually ripens to yellow. Together with the withered flower, the fruit looks like a miniature pineapple. Because the fruit is relatively dry, it does not rot away like the fruits of saguaros and prickly pears. It is common to have the fruit remain on the plant for a year – until something picks it off.

I especially like barrel cactus fruit because it is the only one without spines; it can be picked and eaten raw right off the plant; both the flesh and the seeds inside can be eaten raw or cooked. The flesh is slightly mucilaginous (slimy like okra). The taste is tart; somewhere between lemon and kiwi fruit. The seeds may be separated and ground to a mush. If you pick a fruit that has been on the cactus for sometime, check for insects unless you don’t mind the extra protein. The flower buds can be eaten also. The buds were often boiled and used like cabbage by native tribes.

Cactus fruit in general is rich in vitamin A and vitamin C. There is clinical evidence that the juice of the fruit of prickly pears lowers blood cholesterol. This may be a characteristic of most cactus fruit, but only prickly pears have been tested so far. If you have a barrel cactus in the yard, and the fruit is yellow, try taking a bite, they are good.

You may notice that barrel cacti frequently lean in one direction – toward the south. This is a reliable indicator of direction in the desert. They lean south so the top can get the most sunlight.

It is reported that Seri Indians sometimes used the Fishhook barrel for emergency water. However, drinking the juice on an empty stomach often causes diarrhea, and some Seri report pain in their bones if they walk a long distance after drinking the juice. The Seri called the Coville, “barrel that kills” because eating the flesh of the cactus (not the fruit) causes nausea, diarrhea, and temporary paralysis, but the pulp can be used as an external analgesic.

Enjoy the fruit of the desert.

Reference: A Natural History of the Sonoran Desert, Arizona-Sonora Desert Museum.

Most mineral deposits are just curiosities. Those that make mines are extraordinary and rare. Some people insist on reclamation of a mine soon after it is mined out. For some kinds of mines, such as a coal mine, it is obvious when the mineral is gone and the mined land can be reclaimed. However, metal mines, particularly large copper mines, can have many lives and be “mined out” many times. For these mines, wholesale reclamation such as filling in an open pit is uneconomic, wasteful, and unsound environmental practice, because it takes less toll to reopen an old mine than to construct a new one. This story concerns the large copper deposits of southern Arizona and New Mexico; mines which produce about 66% of the nation’s domestically mined copper; mines which have many lives.

To understand how a mineral deposit can have many lives, we must appreciate the difference between mineralization and ore. “Ore” is that part of the mineralization which can be extracted at a profit. The term “ore” is purely economic and at any given time, it depends on the price of the commodity, the current technology, the costs of extraction and beneficiation, and the regulatory climate. A particular volume of mineralization can be classified as ore or removed from that classification. Government regulation is adding more and more cost, thereby decreasing “ore”, the amount of mineralization than can be made available to us.

The history of each large copper mine in the Southwest is unique, but their stories are similar. This essay, a composite of those histories, concerns the Copper King mine, a fictional name based on a medium-sized “porphyry” copper deposit. Commonly, large mineral deposits experience mining in some form over long periods of time, more than 125 years so far for the Copper King. The ability to provide raw materials over such a long time span is possible because different parts of the deposit are mined in response to changing economy and technology.

For hundreds of years, aboriginal people mined small quantities of the decorative green and blue oxide minerals and native copper at the Copper King mine site. Eventually, however, they could no longer extract material using their primitive tools. For them, the site became mined out.

Modern recorded activity began in the 1870s when turquoise attracted attention of local ranchers. Turquoise was mined with hand tools from small pits on veins, but production was spotty due to the remoteness of the mine and frequent attacks by aborigines. As time progressed, prospectors found the rich veins of chalcocite (a copper sulfide) which also were exploited with hand tools and primitive machines. Activity remained on a small scale, however, because only the richest mineralization could pay for the cost of transportation to the distant smelters by pack mule and wagon. Chalcocite ore mined at this time had a copper content of 30% copper per ton of rock and it was soon exhausted. The mine was mined-out.

In the 1890s, a newly constructed railroad, part of the transcontinental system, provided a more economical means of getting bulk ore to market. Lower transportation costs made lower-grade mineralization “ore” and allowed several mining companies to exploit the rich veins by costlier underground mining methods. The rock mined at this stage had a copper content of 4% to 10% copper per ton. Some companies prospered; others did not. Eventually, one company bought out all others and consolidated the mining camp into one operation for more efficient production. Underground mining of veins continued until the early 1920s, providing copper for the war effort in World War I. After the war, copper prices plunged and the mines closed. The remaining veins were not rich enough or numerous enough to support the cost of mining and processing. Again the mine was mined out.

During the ensuing years, geologists were at work in other areas creating ideas about disseminated mineral deposits, those with mineralization dispersed throughout the rock rather just confined to veins. Mining companies developed equipment enabling bulk mining of large, low-grade deposits with copper grades of 1% or less.

One key advance was the development of concentrating low-grade ore minerals by flotation extraction milling. This is a process where the mined rock is crushed to a consistency of talcum powder, and then transferred to large tanks which contain a stirring arm, much like a slow-speed blender or food processor. This same equipment is now used in some paper pulp mills. Within the tank, a mixture of powdered rock, water and pine oil is injected with air to form bubbles. The rock material, or gangue, sinks to the bottom of the tank. The ore minerals become attached to the bubbles through chemical attraction and surface tension, and float to the top where they are skimmed or “floated” off. The skimmed material, called concentrate, contains about 30% copper produced from rock originally containing 1% copper or less. The concentrate is dried, then sent to a smelter. Some by-product metals, such as molybdenum, lead or zinc, can be extracted in the concentrator through separate circuits. Other metals, such as gold and silver remain with the copper and are extracted in the refinery.

In the late 1940s, geologists thought these “new” techniques could be applied to the Copper King. During the 1950s and early 1960s, the low-grade disseminated chalcocite and chalcopyrite (CuFeS2) mineralization was explored with over 1000 drill holes. Finally, in the mid-1960s, the drilling had delineated mineralization of sufficient quantity and grade that it could be classified as ore based on new bulk mining and milling techniques. The exploration work and new technology lead the Copper King Mining Company to justify expenditure of several hundred million dollars for construction of an open pit mine, a concentrator, and purchase of equipment including large trucks and power shovels. Mining of this new, lower-grade chalcocite and chalcopyrite began in the 1960s.

By the late 1980s, however, mineralization grading over 0.4% copper per ton, the minimum required for the concentrator, was getting scarce and the Copper King was facing the end of its current stage of economic life. Again, it would become mined out. However, during the last years of mining, a new process was perfected: electrowinning-solvent extraction (SX/EW). This process allowed recovery of copper from even lower-grade chalcocite and, for the first time, economic extraction of copper from oxide mineralization which could not be processed by flotation. However, this method could not deal with the primary chalcopyrite.

The solvent extraction part of the SX/EW process is very similar to the natural process which formed the chalcocite and oxide mineralization. Rock is mined and placed in large, tabular heaps, usually 25 to 50 feet high, covering several acres. Slightly acidic water is sprayed on the heaps and allowed to percolate downward. The water dissolves copper in the rock. The copper-rich water is collected and piped to the extraction plant where copper is first stripped from the water using an organic solvent such as kerosene. The water is recycled. Copper-rich solution is pumped to a tank house. The tanks are like large automobile batteries, but run in reverse by applying electricity causing the copper to plate out on one of the “battery” electrodes. The SX/EW method is much less costly than the concentration process because it produces copper of sufficient purity for market without going through a concentrator or smelter. The SX/EW process is also more environmentally friendly. There are trade-offs, however. SX/EW cannot recover by-product metals such as molybdenum, gold and silver, nor can it recover copper from chalcopyrite.

SX/EW processing began during the later stages of mining at the Copper King and supplemented the concentrator ore, and continued alone after the concentrator closed. Because SX/EW can process lower-grade chalcocite and oxide minerals, it led to more geological investigation and exploration drilling which identified hundreds of millions of tons of formerly worthless rock which could now be classified as ore using the new process. Now all chalcocite, rich veins and low-grade disseminations alike, containing as little as 0.3% copper per ton could be mined. In addition, all the oxide material, which could not previously be exploited on large scale, could be mined to grades as low as 0.1% copper per ton.

In about 2003, a mining company perfected a method of leaching chalcopyrite in real time. This made possible the relatively inexpensive extraction of lower-grade chalcopyrite (more mineralization became “ore”) and it also eliminated the need for expensive smelting.

Under the new technology, the sulfide slurry from the concentrator is pumped into a pressure tank at 600 psi and heated to 225 C. Addition of oxygen causes the sulfides to break down according to this formula: Chalcopyrite + oxygen + water becomes aqueous copper sulfate + hematite + sulfuric acid. The reaction is written: 4 CuFeS₂ + 17 O₂ + 4 H₂O = 4 CuSO₄ + 2 Fe₂O₃ + 4 H₂SO₄.

Pyrite undergoes a similar reaction to produce hematite and sulfuric acid: 4 FeS₂ + 15 O₂ + 8 H₂O = 2 Fe₂O₃ + 8 H₂SO₄. These reactions are similar to the natural weathering process which occurs over thousands of years. Pressure leaching does it in one hour.

By-product gold and silver, if any, stays with the hematite and can be recovered through conventional cyanidation leaching after the solids are removed from the reaction vessel. The sulfuric acid can be used to leach oxide copper ores. The aqueous copper sulfate goes to the solvent extraction – electrowinning (SX/EW) plant.

The Copper King mine will continue into the future, but what then? All mining since 1870 or any that will occur in the next few decades will have exploited only the top 1000 feet of the 7000-foot thick mineral deposit. Most of the remaining material is low-grade chalcopyrite (about 0.3% copper or less), material not economically extractable now. At that time, will the mine finally be mined out? No! New technological processes will be developed to economically extract some or much of the remaining copper.

One such process under development is the dissolution of chalcopyrite using sulfur-eating bacteria which can exist only in the environment of the sulfide mineralization. When this method is fully developed, it could allow leaching of chalcopyrite in situ (in place underground) and give the mine another life. It could also allow leaching of very low grade mine tailings left from previous mining operations.

The Copper King mine has had a long life, often marked by periods of inactivity: periods awaiting changes in economics or technology, periods awaiting a development which will turn mineralization into ore. Those who say that we should fill in open pits are short sighted because that activity may make a mine uneconomic at the outset and could make future mining based on new technology impossible. It is more environmentally sound to find ways to continue mining at an existing mineral deposit than to find and exploit a new deposit on virgin ground.

Mining is a risky business which requires huge up-front expenditures. It ultimately depends on economics. The engineering factors, such as deposit geometry and cost of equipment can be calculated with reasonable certainty. Other costs, especially that of ever-changing government regulation in the form of royalty schemes or environmental laws, make mining risky indeed and may actually waste a portion of the natural resource by drastically decreasing the amount of mineralization that can be called ore.

Have you ever noticed that some prickly pear pads around town have white fuzzy stuff on them? Under the fuzzy stuff, which is a waxy web, is a little red bug called a Cochineal. Scientific name: (Dactylopius cocus)

The story of the Cochineal is fascinating and you may often use something it produces.

When the Spaniards first came to Mexico in the early 1500s, they sought gold. They also found another substance which became just as valuable: a substance that would lead to a world-wide commercial monopoly, a substance that was the object of international industrial espionage; and a substance which caused them to import prickly pear cacti to Spain.

When Hernan Cortes came to Mexico in 1523, he noticed that the natives were wearing brilliant red clothing. He also saw that the color didn’t fade upon washing. He found the perfect red dye, something Europeans had been seeking for centuries. Where did this remarkable dye come from?

The cochineal is a scale insect which feeds on the juices of the prickly pear. To protect itself from the sun, it spins a waxy, white web. To protect itself from predators, mainly ants, it produces Carminic Acid, a very bitter-tasting substance. And carminic acid is the best natural red dye there is.

Female cochineals are dark red, wingless, legless, and sessile (attached to the plant and sedentary). Males resemble small pink and white gnats.

Males undergo complete metamorphoses and develop into winged adults. Females, however, remain in a prolonged larval stage, never changing into winged adults, but becoming sexually mature nonetheless.

The young females settle near their mother in groups and secrete the fluffy wax which protects them from desiccation. Each female sticks its tube-like proboscis into the cactus pad and draws nutrients from the cactus throughout its three-year life-span. Within a few weeks of hatching, the female becomes bloated and sexually mature – a silvery, purplish balloon, similar to a fully engorged tick. When home sites become too crowded, the young females use web material to ride the wind to another pad.

The male cochineal remains tiny and mobile. After a few weeks, he spins a cocoon-like structure and transforms himself into a tiny, soft-bodied, delicate-winged flyer. The male lacks mouth parts, and is programed for one thing, sex, and that he pursues by moving rapidly among the cactus pads and mating with as many females as possible before he dies within about a week.

To produce dye, the bugs are harvested, dried, and boiled. The material to be dyed is placed in vats of the mixture and the color is fixed with oxalic acid obtained from juices of several plants including the cacti themselves.

The Spaniards knew a good thing when they saw it. Cochineal dye was so good, that the bugs and cacti were exported to Spain and to Spanish colonies in South America, and the dye soon took over the market. That, incidentally is why you can find prickly pear cactus in Europe.

For almost 300 years, Spain had a monopoly in Cochineal dye and they strictly controlled the source. One of their best customers was the British Army. The Redcoats red came from the cochineal.

The French didn’t like this and constantly tried to get some of the little red bugs. Finally, in 1787, a French naturalist manage to smuggle Cochineal-laded cacti out of Mexico to Haiti where they too began producing the dye. In the 1870s, the English managed to get some cactus and cochineal, and tried to grow them in India.

Cochineal dye is still produced in Mexico, Spain, and South America.

Red dye from the Cochineal is not used much for clothing any more since it has been replaced by synthetic dyes. However, Cochineal dye is widely used in cosmetics and in food coloring. It is non-toxic and non-carcinogenic. Read the labels of any red food product. If you see the word Carmine (or sometimes cochineal), then the red color comes from the mashed remains of the little red bug that lives under the white fuzz dotting prickly pear pads.

Pristine: “belonging to the earliest period or state; uncorrupted by civilization.”

We often hear the plea from preservationists that we must save the pristine desert, or stream, or forest, or jungle, or whatever, because these are the “last best places” untrammeled by man. But are they really so pristine?

Archaeological and anthropological research during the last 15 years or so, shows that much of what we thought was pristine in the Western Hemisphere, even the Amazon rain forest, is actually human-formed landscape created by the first New World inhabitants, the Indians. It seems that American Indians, from North America, Mexico and South America, were the ultimate land managers, and they transformed the land to suit their needs. They constructed the world’s largest gardens.

The quest of some preservationists to return the land to pre-Columbian times, to its state prior to 1492, is a quest in pursuit of a myth. “The pristine view is to a large extent an invention of nineteenth-century romanticist and primitivist writers such as W.H. Hudson, Cooper, Thoreau, Longfellow, and Parkman, and painters such as Catlin and Church.”¹ Reality, according to the new research, is quite different.

The Amazon forest in the Beni region of Bolivia consists of “an archipelago of forest islands, many of them startlingly round and hundreds of acres across. Each island rose ten or thirty or sixty feet above the floodplain, allowing trees to grow that would otherwise never survive the water. The forests were linked by raised berms, as straight as a rifle shot and up to three miles long.”² Researcher Clark Erickson of the University of Pennsylvania believes “that the entire landscape, 30,000 square miles of forest mounds surrounded by raised fields and linked by causeways, was constructed by a complex, populous society more than 2,000 years ago.”² “A growing number of researchers have come to believe that Indian societies had an enormous environmental impact on the jungle. Indeed, some anthropologists have called the Amazon forest itself a cultural artifact, that is, an artificial object.”²The 1539 expedition of Hernando de Soto across what is now the southeastern U.S. encountered not some primeval forest, but “thickly settled land, very well peopled by large towns.”² In 1519, Hernan Cortes saw that the Aztec capital of Tenochtitlan was bigger than Paris and contained “wide streets, ornately carved buildings, and markets bright with goods from hundreds of miles away.”² Even the first settlers in the northeastern U.S. found that forests were open and park-like, not the dense grow romanticized by writers hundreds of years later.

Many researchers estimate that the Americas were well-populated before the arrival of Columbus, with a population of between 40- to 80 million, greater than the population of Europe at the time. “Moreover, the native impact on the landscape of 1492 reflected not only the population then but the cumulative effects of a growing population over the previous 15,000 years or more.”¹American Indians built cities and civilizations, cultivated forests and farms, and developed more than half of the crops grown worldwide today. Indians, rather than subsist passively on what wild nature provided, instead “survived by cleverly exploiting their environment.”² Their principal tool was fire.³ They did not domesticate animals for meat, but instead used fire to change whole ecosystems to raise deer, elk, and bison. “Millennia of exuberant burning shaped the plains into vast buffalo farms.”²

But then the Europeans came and unintentionally brought with them smallpox, typhus, influenza, diphtheria and measles, (and later on cholera, malaria, and scarlet fever). Within about 130 years after first contact, 95% of the native population was wiped out by disease.² By 1682, when French explorers retraced de Soto’s journey, they found the land nearly deserted. Because the hunters were gone, buffalo, elk, and deer populations exploded. Because the fire-using land managers were gone, dense forests, romanticized by 19^th century writers had taken over the carefully managed forest parks. In one sense, Europeans did not destroy pristine wilderness, but recreated it.

By “1492, Indian activity had modified vegetation and wildlife, caused erosion, and created earthworks, roads, and settlements throughout the Americas. This may be obvious, but the human imprint was much more ubiquitous and enduring than is usually realized. The historical evidence is ample, as are data from surviving earthworks and archaeology. And much can be inferred from present human impacts. The weight of evidence suggests that Indian populations were large, not only in Mexico and the Andes, but also in seemingly unattractive habitats such as the rainforests of Amazonia, the swamps of Mojos (Bolivia), and the deserts of Arizona.”¹

I would argue that humans have enriched the land by making it produce more, and have increased diversity by creating more habitats than would otherwise occur. When preservationists whine about losing our “pristine” desert, and pine for a return to Walden, when the “vision” statements of federal land management agencies speak grandiosely of ecosystem management in search of the pristine myth, remind them that nature is not so pristine. It is always changing. The “forest primeval” doesn’t exist.

References:

1: Denevan, William M., ca. 1992, The Pristine Myth: The Landscape of the Americas in 1492, Department of Geography, University of Wisconsin.

2: Mann, Charles C., 2002, 1491, The Atlantic Monthly, March 2002.

3:Krech, Shepard, 1999, The Ecological Indian, W.W. Norton & Co.