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Geology of the National Parks - Death Valley

 

Composition and occurence of salt minerals in Death Valley

SOURCE: US Geological Survey Professional Paper 494
Hunt, C.B., and Mabey, D.R., 1966, General Geology of Death Valley, California

Mineral

Composition

Known or probable occurrence

Halite

NaCl

Principal constituent of chloride zone and of salt-impregnated sulfate and carbonate deposits.

SyIvite

KCI

With halite.

Nahcolite

NaHCO3

Not yet identified; might be found in wintertime as efflorescence or trona or thermonatrite in carbonate zone in Cottonball Basin.

Trona

Na3H(CO3)22H2O

Carbonate zone of Cottonball Basin, especially in marshes.

Thermonatrite

Na2CO3·H2O

Questionably present on floodplain in Badwater Basin, would be expected in marshes of carbonate zone in Cottonball Basin.

Natron

Na2CO3·10H2O

Not yet identified but may be expected, especially In winter, immediately following rains or periods of high discharge at marshes in carbonate zone in Cottonball Basin.

Pirssonite

Na2Ca(CO3)2·2H2O

Not yet identified, may be expected in environments where gaylussite would be dehydrated.

Gaylussite

Na2Ca(CO3)2·5H2O

Carbonate zone and floodplain in Badwater Basin.

Calcite

CaCO3

Occurs as clastic grains in sediments underlying salt pan and as sharply terminated crystals in clay fraction of carbonate zone and in sediments underlying sulfate zone.

Magnesite

MgCO3

Obtained in artificially evaporated brines from Death Valley; not yet identified in salt pan; may be expected in carbonate zone of Cottonball Basin.

Dolomite

CaMg(CO3)2

identified only as a detrital mineral; may be expected in carbonate zone.

Northupite

and/or

Tychite

Na3MgCl(CO3)

 

Na6Mg2(SO4)·(CO3)4

An isotropic mineral, having index of refraction in the range of Northupite and Tychite, has been observed in saline facies of sulfate zone in Cottonball Basin.

Burkeite

Na6(CO3)(SO4)2

Sulfate zone in Cottonball Basin.

Thenardite

Na2S04

Common in all zones in Cottonball Basin and in sulfate marshes in Middle and Badwater basins.

Mirabilite

Na2S04·10H2O

Occurs on floodplains in Cottonball Basin immediately following winter storms.

Glauberite

Na2Ca(SO4)2

Common on floodplains except in central part of Badwater Basin; sulfate zone in Cottonball Basin.

Anhydrite

CaSO4

As layer capping massive gypsum I mile north of Badwater. Possibly also as dry-period efflorescence on floodplains.

Bassanite

2CaSO4·H2O

As layer capping massive gypsum along west side of Badwater Basin and as dry-period efflorescence in floodplains.

Gypsum

CaS04·2H2O

In sulfate caliche, layer in carbonate zone, particularly in Middle and Badwater basins, in sulfate marshes and as massive deposits in sulfate zone.

Hexahydrite

MgS04·6H2O

Not yet identified but might he expected as dehydration product of epsomite in chloride zone on floodplains.

Epsomite

MgS04·7H2O

Not yet identified; probably will he found as efflorescence on floodplains following storms or floods would dehydrate to hexahydrite during dry periods.

Bloedite

Na2Mg(SO4)2·4H2O

Questionably present in efflorescence on floodplain in chloride zone.

Polyhalite

K2Ca2Mg(SO4)4·2H2O

Questionably present on floodplain in chloride zone.

Barite

BaS04

Not yet identified but probably will be found in carbonate zone and as clastic grains in sediments underlying salt pan.

Celestite

SrSO4

Found with massive gypsum.

Schairerite

Na3(SO4)(F,Cl)

Not yet identified, might he expected in Cottonball Basin or east side of Middle Basin.

Sulfohalite

Na6ClF(SO4)2

Not yet identified, might he expected in Cottonball Basin or east side of Middle Basin.

Kernite

Na2B4O7·5H2O

Possibly present in Middle Basin in surface layer of layered sulfate and chloride salts.

Tincalconite

Na2B4O7·10H2O

Probably occurs as dehydration product of borax.

Borax

Na2Mg(SO4)2·4H2O

Floodplains and marshes in Cottonball Basin.

Inyoite

Ca2B6O11·13H2O

Questionably present (X-ray determination but unsatisfactory) in floodplain in Badwater Basin.

Meyerhofferite

Ca2B6O11·7H2O

Found in all zones in Badwater Basin and in rough silty rock salt in Cottonball Basin

Colemanite

Ca2B6O11·5H2O

Questionably present (X-ray determination but unsatisfactory) in floodplain in Badwater Basin.

Ulexite

NaCaB5O9·8H2O

Common in floodplain in Cottonball Basin; known as "cottonball"

Proberite

NaCaB5O9·5H2O

A fibrous borate with index of refraction higher than ulexite occurs on dry areas in Cottonball Basin following hot dry spells and in surface layer of smooth silty rock salt.

Soda niter

NaNO3

Weak, but positive chemical tests obtained locally.

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