Gilbertite
A variety of Muscovite
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About Gilbertite
Davies Gilbert
Formula:
KAl2(AlSi3O10)(OH)2
Name:
Named in 1831 by Thomas Thomson in honor of Davies Gilbert [6 March 1767, Penzance, Cornwall, England, UK - 24 December 1839 Eastbourne, East Sussex, England, UK. His original name was Giddy, but he changed his surname to Gilbert on 10 December 1816, to match the surname of his wife's uncle. Although trained as an engineer, his career was primarily political and he held positions as sheriff, member of the Board of Agriculture, and a vice-president of the Royal Society. In Parliament (1804-1832), he was a conservative who voted for industrialization and mining interests, redistricting, and was widely regarded for his great mathematical abilities as well as interests in antiquarian subjects. When gilbertite was named, Gilbert was the representative for Bodmin, where the Stenagwyn Mine is located.
A variety of Muscovite
Compact variety of muscovite.
The original chemical analysis of material from Stenagwyn, Cornwall, indicated no potassium or sodium ( Thomson, 1831). There were major amounts of silica and alumina, and minor amounts of CaO, MgO, and FeO. Thomson seems to have doubted the validity of his own mineral and suggested it was a mica, although, in the time period, micas were still poorly understood.
Compact variety of muscovite.
The original chemical analysis of material from Stenagwyn, Cornwall, indicated no potassium or sodium ( Thomson, 1831). There were major amounts of silica and alumina, and minor amounts of CaO, MgO, and FeO. Thomson seems to have doubted the validity of his own mineral and suggested it was a mica, although, in the time period, micas were still poorly understood.
Unique Identifiers
Mindat ID:
1692 (as Gilbertite)
2815 (as Muscovite)
2815 (as Muscovite)
Long-form identifier:
mindat:1:1:1692:2 (as Gilbertite)
mindat:1:1:2815:4 (as Muscovite)
mindat:1:1:2815:4 (as Muscovite)
GUID
(UUID V4):
(UUID V4):
6d3a551b-33de-443c-8243-1a6e8d8b8a06 (as Gilbertite)
6555d00d-e8c3-4485-9209-15e6b685a47f (as Muscovite)
6555d00d-e8c3-4485-9209-15e6b685a47f (as Muscovite)
Chemistry of Gilbertite
Mindat Formula:
KAl2(AlSi3O10)(OH)2
Other Language Names for Gilbertite
German:Gilbertit
Spanish:Gilbertita
Common Associates
Associated Minerals Based on Photo Data:
| 15 photos of Gilbertite associated with Fluorapatite | Ca5(PO4)3F |
| 15 photos of Gilbertite associated with Cassiterite | SnO2 |
| 14 photos of Gilbertite associated with Orthoclase | K(AlSi3O8) |
| 8 photos of Gilbertite associated with Quartz | SiO2 |
| 7 photos of Gilbertite associated with Smoky Quartz | SiO2 |
| 6 photos of Gilbertite associated with Albite | Na(AlSi3O8) |
| 6 photos of Gilbertite associated with Fluorite | CaF2 |
| 6 photos of Gilbertite associated with Microcline | K(AlSi3O8) |
| 5 photos of Gilbertite associated with Tourmaline | AD3G6 (T6O18)(BO3)3X3Z |
| 4 photos of Gilbertite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
Fluorescence of Gilbertite
Not fluorescent in UV
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 Gilbertite
mindat.org URL:
https://www.mindat.org/min-1692.html
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References for Gilbertite
Localities for Gilbertite
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.
Czech Republic | |
| Rojík (2006) |
France | |
| Queneau (n.d.) |
| perso.wanadoo.fr (2005) |
Germany | |
| Habel (2009) |
| |
| Weiß (1990) | |
| Weiß (1990) |
| Weiß (1990) |
| Weiß (1990) |
| Weiß (1990) | |
| 54. +1 other reference |
| Hirschmann (1987) |
| Lapis 1991 (10) |
| Vollstädt (1979) |
| Wittern (2001) |
Jersey | |
| Mourant (1978) |
| Mourant (1978) |
Kazakhstan | |
| Oitseva et al. (2017) |
Madagascar | |
| Behier (1963) |
| Guigues (1955) |
| Behier (1960) |
| Behier (1963) |
Portugal | |
| |
Russia | |
| M.M. Povilaitis data (http://klopotow.narod.ru/mindata/locathn/R_Buryat/zakamensk/djida.html) |
| Rundqvist (1997) |
| D’yachkov et al. (2022) |
Slovakia | |
| Koděra (1986) |
UK | |
| Hill et al. (1906) |
| P Haas collection | |
| Stephens (1895) |
| Russell (1910) +2 other references |
| Bowman (1911) |
| |
| Dines (1956) |
| Dines (1956) |
| Rowe et al. (1879) +1 other reference |
| Hall (1868) +2 other references |
| Ussher et al. (1909) |
| |
| Barstow (1982) +1 other reference |
| Dominy et al. (1996) |
| Dominy et al. (1996) |
| Dominy et al. (1996) | |
| Hall (1868) +1 other reference |
| Min Mag 21:116-205 |
Cornwall, England, UK