Hilgardite-3Tc
A structural variant of Hilgardite
This page is currently not sponsored. Click here to sponsor this page.
Colour:
Colourless; colourless in transmitted light
Lustre:
Vitreous
Hardness:
5
Crystal System:
Triclinic
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.
Unique Identifiers
Mindat ID:
9762
Long-form identifier:
mindat:1:1:9762:4
GUID
(UUID V4):
(UUID V4):
c4d06072-a1f4-4e45-be7d-49d293c314f1
Physical Properties of Hilgardite-3Tc
Vitreous
Transparency:
Transparent
Colour:
Colourless; colourless in transmitted light
Hardness:
5 on Mohs scale
Cleavage:
Perfect
On {010} and {100}.
On {010} and {100}.
Optical Data of Hilgardite-3Tc
Type:
Biaxial (+)
Dispersion:
r > v
Crystallography of Hilgardite-3Tc
Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
Cell Parameters:
a = 11.24 Å, b = 22.28 Å, c = 6.2 Å
α = 90°, β = 90°, γ = 91.2°
α = 90°, β = 90°, γ = 91.2°
Ratio:
a:b:c = 0.504 : 1 : 0.278
Unit Cell 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:
| Hilgardite | Ca2B5O9Cl · H2O |
Epitaxy Comments:
Parahilgardite {100} [001] parallel with Hilgardite {100} [001], with the {010} cleavages of the two minerals inclined at 1°12'.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.87 Å | (100) |
| 2.83 Å | (100) |
| 2.755 Å | (80) |
| 2.12 Å | (80) |
| 2.033 Å | (80) |
| 5.7 Å | (60) |
| 3.14 Å | (60) |
Comments:
Choctaw salt dome, Louisiana, USA.
Synonyms of Hilgardite-3Tc
Other Language Names for Hilgardite-3Tc
German:Parahilgardit
Russian:Хилгардит-3Tc
Парахильгардит
Парахильгардит
Simplified Chinese:副氯羟硼钙石
Spanish:Parahilgardita
Traditional Chinese:副氯羥硼鈣石
Common Associates
Associated Minerals Based on Photo Data:
| 4 photos of Hilgardite-3Tc associated with Hilgardite | Ca2B5O9Cl · H2O |
| 4 photos of Hilgardite-3Tc associated with Boracite | Mg3(B7O13)Cl |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Hilgardite-3Tc
mindat.org URL:
https://www.mindat.org/min-9762.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
Mineral Dealers:
References for Hilgardite-3Tc
Reference List:
Localities for Hilgardite-3Tc
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
China | |
| Li et al. (2015) |
UK | |
| Milne (1978) |
| Smith et al. (2014) |
USA | |
| Rocks & Minerals: 69 (3) +2 other references |
