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Hilgardite-3Tc
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| System: | Triclinic | Colour: | Colourless; colourless ... |
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| Hardness: | 5 | ||
| Name: | Named for Eugene Woldemar Hilgard (1833-1916), German-American geologist, one of the first to describe the Loiuisiana salt dome deposits. | ||
A polytype of Hilgardite
Originally described from Choctaw Salt Dome, Iberville Parish, Louisiana, USA.
Originally described from Choctaw Salt Dome, Iberville Parish, Louisiana, USA.
Classification of Hilgardite-3Tc | ||||||||||||||||||||
| mindat.org URL: | http://www.mindat.org/min-9762.html Please feel free to link to this page. | |||||||||||||||||||
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Physical Properties of Hilgardite-3Tc | ||||||||||||||||||||
| Lustre: | Vitreous | |||||||||||||||||||
| Diaphaneity (Transparency): | Transparent | |||||||||||||||||||
| Colour: | Colourless; colourless in transmitted light | |||||||||||||||||||
| Hardness (Mohs): | 5 | |||||||||||||||||||
| Cleavage: | Perfect On {010} and {100}. | |||||||||||||||||||
Crystallography of Hilgardite-3Tc | ||||||||||||||||||||
| Crystal System: | Triclinic | |||||||||||||||||||
| Class (H-M): | 1 - Pedial | |||||||||||||||||||
| Space Group: | P1 | |||||||||||||||||||
| Cell Parameters: | a = 11.24Å, b = 22.28Å, c = 6.2Å α = 90°, β = 90°, γ = 91.2° | |||||||||||||||||||
| Ratio: | a:b:c = 0.504 : 1 : 0.278 | |||||||||||||||||||
| Unit Cell Volume: | V 1,552.31 ų (Calculated from Unit Cell) | |||||||||||||||||||
| Z: | 2 | |||||||||||||||||||
| Morphology: | Only occurs as oriented intergrowths with hilgardite. The intergrowths are comprised of two partly merged individual crystals of Hilgardite-3Tc, one right-handed and one left-handed, in apparent twin position. These are attached by the positive end of [100] to (100) of a single Hilgardite crystal. Common forms include b, p, t. | |||||||||||||||||||
Epitaxial Relationships of Hilgardite-3Tc | ||||||||||||||||||||
| Epitaxial Minerals: |
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| Epitaxi Comments: | Parahilgardite {100} [001] parallel with Hilgardite {100} [001], with the {010} cleavages of the two minerals inclined at 1°12'. | |||||||||||||||||||
Optical Data of Hilgardite-3Tc | ||||||||||||||||||||
| Type: | Biaxial (+) | |||||||||||||||||||
| Dispersion: | r > v | |||||||||||||||||||
Other Names for Hilgardite-3Tc | ||||||||||||||||||||
| Synonyms: |
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Other Information | ||||||||||||||||||||
| Health Warning: | No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care. | |||||||||||||||||||
References for Hilgardite-3Tc | ||||||||||||||||||||
| Reference List: - + | Hurlbut (1938) American Mineralogist: 23: 765 (as Parahilgardite). Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 383 (as Parahilgardite). American Mineralogist (1985): 70: 636-637. | |||||||||||||||||||
Internet Links for Hilgardite-3Tc | ||||||||||||||||||||
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Localities for Hilgardite-3Tc | ||||||||||||||||||||
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The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the
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(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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