Death Valley

Talc of metasedimentary origin is formed by hydrothermal alteration of a dolomitic host rock by a silica-containing fluid. This type of deposit is typical of Montana and AustraUa. It is usually quite pure with talc content of 90 to 98% and often very white as well. Dolomite [17069-72-6], CaMg(C02)2, is the most common accessory mineral. The fourth type is of metamorphic origin, where a siUcaceous dolostone is first converted to tremolite [14567-73-8] or actinohte [13768-00-8] and then partially converted to talc. The Balmat, New York, and Death Valley, California, deposits are of this type. Tremolite, dolomite, and serpentine are common accessory minerals. This type of talc deposit has a variable talc content (30—80%), but is usually white and often commercially exploited because of the properties of its accessory minerals rather than the talc. 

Death Valley, Calif. colemanite, ulexite, probertite several... 

Death Valley, California, has historically been a significant source of both colemanite and ulexite, but mining in the Death Valley National Monument has been forbidden as a result of environmental concerns. In 1986, the American Borate Co. ceased mining in Death Valley, but continues to market ore concentrate from inventory as well as borates and concentrates imported from Turkey. 

M. S. Roberts, L. K. Nakamura, and F. M. Cohan, Bacillus vallismortis sp nov, a close relative of Bacillus subtilis, isolated from soil in Death Valley, California, hit. J. Sys. Bacteriol. 46 470 (1996). 

Kn T-L, Lno S, Lowenstein TM, Li J (1998) U-series chronology of lacustrine deposits in Death Valley, California. QuatRes 50 261-275... 

The United States and Turkey are the world s largest producers of boron.1 Economically important sources are from the ores rasorite (kernite) and tincal, which are both found in the Mojave Desert of California, with borax being the most important source there. The famous 20-Mule-Team Borax, now a part of chemistry folklore, originates from the time when teams of 20 mules used to haul colemanite from Furnace Creek in Death Valley 166 miles south to Mojave. Elemental boron in its impure form can be obtained by the reduction of the oxide B203 by magnesium, and in the pure form by the reduction of BC13 by hydrogen on hot filaments.1... 

Compare the two results. What would be the maximum 1,4-DCB concentration in the air of a public toilet located in Death Valley (temperature 60°C) Any comments ... 

How does the density of air in Death Valley, which is 86 meters below sea level, compare with the density of air at sea level Explain. 

Less than a hundred years ago, a mineral called borax, containing the element boron, was carted out of Death Valley in California by twenty-mule teams — about the slowest transportation you can think of. Someday, boron may be put in zip-fuels for space missiles — the fastest form of transportation imaginable. Boron has the ability (as does carbon) to... 

Some of the hottest land temperatures on earth—up to 134°F—have been recorded at Death Valley, California. 

Salt deposits or evaporites precipitate from evaporating seawater that becomes trapped in semi-isolated marine basins. Salty desert lakes, such as Great Salt Lake, Utah, USA, or those in Death Valley, California, USA, are also sites of evaporite deposition. Common salt minerals include halite (NaCl), sylvite (KC1),... 

Trull, T. W., Brown, E. T., Marty, B., Raisbeck, G. M., Yiou, F. (1995) Cosmogenic 10Be and 3He accumulation in Pleistocene beach terraces in Death Valley, California, U.S.A. Implications for cosmic-ray exposure dating of young surfaces in hot climates. Chem. Geol., 119, 191-207. 

A. P. Bahnemann, D. W. Hoffmann, M. R.. T. Phvs. Chem. accepted for publication 12/12/86). These particles have a mean diameter of 30 nm with 30% of the surface area covered with Co(II)TSP. Desert sand obtained from Death Valley has been treated with several acid washing cycles and selected by size and weight (Kormann, C. Bahnemann, D. W. Hoffmann, M. R. unpublished data). The H202 concentration was measured continuously with a YSI-Clark 2510 Oxidase Probe connected to a YSI model 25 oxidase meter. The surface of the electrode was covered with a dialysis membrane (molecular weight cutoff 12,000 - 14,000) to prevent any... 

Figure 4. Formation and depletion of H202 upon illumination and in the dark observed in an aerated aqueous suspension of Death Valley desert sand (other exp. cond. are given in the figure).

An old ad from The Saturday Evening Post for Boraxo, a hand-cleaning product containing sodium tetraborate (NaB407). Extensive natural deposits of borax (Na2B407 10H20) found in saline lakes near Death Valley, California, were hauled to a factory in wagons pulled by teams of 20 mules-hence the name 20 Mule Team Borax. 

Yang W., Spencer R. J., and Krouse H. R. (1997) Stable isotope composition of waters and sulfate species therein, Death Valley, CaUfomia, USA impUcations for inflow and sulfate sources, and arid basin cUmate. Earth Planet. Sci. Lett. 147, 69-82. 

Several other closed-basin regions are useful as examples of particular brine types. These include the Great Salt Lake (chloride), the lakes of East Africa (carbonate), the northern Great Plains of North America (sulfate), Death Valley (mixed), and the Australian outback (acid-chloride). Representative major ion compositions and SNORM model results for these examples are presented in Tables 3 and 4, respectively. 

At present Death Valley, California (Figure 16), does not contain a perennial lake, but it is an excellent example of a closed-basin system in which several major water types occur (Li et al., 1997). Upland weathering of a wide range of... 

Figure 16 (a) Location of Death Valley, USA (-h) dilute Na-HC03-S04 waters ( ) CI-SO4 waters typical of... 

Li J., Lowenstein T. K., and Blackburn I. R. (1997) Responses of evaporite mineralogy to inflow water sources and climate during the past 100 k.y. in Death Valley. California. Geol. Soc.Am. Bull. 109, 1361-1371. 

Perfect D. L., Eaunt C. C., Steinkampf W. C., and Turner A. K. (1995) Hydrochemical Database for the Death Valley Region, Nevada and California. US Geological Survey Open-File Report 94-305, US Geological Survey. 

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