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3SiO2 · H2O
Specific Gravity:
Crystal System:
Named for its composition: silicon plus water.
This page provides mineralogical data about Silhydrite.

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Classification of SilhydriteHide

Approval Year:

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
M : Hydroxides with H2O +- (OH); unclassified

75 : TECTOSILICATES Si Tetrahedral Frameworks
2 : Si Tetrahedral Frameworks - SiO2 with H2O and organics

7 : Oxides and Hydroxides
8 : Oxides of Si

Physical Properties of SilhydriteHide

2.141 g/cm3 (Measured)    2.116 g/cm3 (Calculated)

Optical Data of SilhydriteHide

relatively weak

Chemical Properties of SilhydriteHide

3SiO2 · H2O
IMA Formula:
Si3O6 · H2O
Common Impurities:

Crystallography of SilhydriteHide

Crystal System:
Cell Parameters:
a = 14.51 Å, b = 18.8 Å, c = 15.93 Å
a:b:c = 0.772 : 1 : 0.847
Unit Cell V:
4,345.51 ų (Calculated from Unit Cell)

Type Occurrence of SilhydriteHide

General Appearance of Type Material:
White, soft, microcrystalline massive material. Material is punky and will float on water when dry (0.65 bulk density). Crystals less than 4 microns in size.
Place of Conservation of Type Material:
Smithsonian, USGS Denver Colorado
Geological Setting of Type Material:
Spring deposit. Formed by leaching of sodium from magadiite from a cold, highly alkaline brine spring. Also found in caves.
Associated Minerals at Type Locality:

Synonyms of SilhydriteHide

Other Language Names for SilhydriteHide


Related Minerals - Nickel-Strunz GroupingHide

4.FM.15FranconiteNa(Nb2O5)(OH) · 3H2OMon.
4.FM.15Hochelagaite(Ca,Na,Sr)(Nb,Ti,Si,Al)4O11 · 8H2OMon.
4.FM.15Ternovite(Mg,Ca)Nb4O11 · nH2OMon.
4.FM.25BelyankiniteCa1-2(Ti,Nb)5O12 · 9H2O (?)Amor.
4.FM.25Gerasimovskite(Mn,Ca)(Nb,Ti)5O12 · 9H2O
4.FM.25Manganbelyankinite(Mn,Ca)(Ti,Nb)5O12 · 9H2O
4.FM.35CuzticiteFe3+2(TeO6) · 3H2OHex.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.8.1QuartzSiO2Trig. 3 2 : P31 2 1
7.8.2CoesiteSiO2Mon. 2/m : B2/b
7.8.3TridymiteSiO2Tric. 1
7.8.4StishoviteSiO2Tet. 4/mmm (4/m 2/m 2/m) : P42/mnm
7.8.5CristobaliteSiO2Tet. 4 2 2 : P41 21 2
7.8.8OpalSiO2 · nH2O

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for SilhydriteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Gude, A.J., Sheppard, R.A. (1972) Silhydrite, 3SiO2•H2O, a new mineral from Trinity County, California. American Mineralogist: 57: 1053-1065.

Internet Links for SilhydriteHide

Localities for SilhydriteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • California
    • Trinity Co.
      • Klamath Mts
        • Trinity Mts
          • Halls Gulch District
            • Wildcat Peak
Gude, A.J. and Sheppard, R.A. (1972) Silhydrite, 3SiO2 •H2O, a new mineral from Trinity County, California. American Mineralogist: 57: 1053-1065; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 357-358;
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