Rhyolite
A rock classification type
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About Rhyolite
Name:
The term was coined in 1860 by Baron von Richthofen (grandfather of the World War I aviator). Etymol: Greek rhyo-, from rhyax, stream of lava.
Rhyolite, with felsic minerals comprising >20% quartz and alkali feldspar/plagioclase 40-90%.
A group of extrusive igneous rocks, typically porphyritic and commonly exhibiting flow texture, with phenocrysts of quartz and alkali feldspar in a glassy to cryptocrystalline groundmass; also, any rock in that group; the extrusive equivalent of granite. Rhyolite grades into rhyodacite with decreasing alkali feldspar content and into trachyte with a decrease in quartz.
A group of extrusive igneous rocks, typically porphyritic and commonly exhibiting flow texture, with phenocrysts of quartz and alkali feldspar in a glassy to cryptocrystalline groundmass; also, any rock in that group; the extrusive equivalent of granite. Rhyolite grades into rhyodacite with decreasing alkali feldspar content and into trachyte with a decrease in quartz.
Unique Identifiers
Mindat ID:
48451
Long-form identifier:
mindat:1:1:48451:8
GUID
(UUID V4):
(UUID V4):
64ee06e1-ac1d-4004-a205-6a15cfbe7199
Classification of Rhyolite
Rhyolite appears in field 3 in the QAPF diagram.
Rhyolite is found in field 'R' in the TAS diagram.
Sub-divisions of Rhyolite
Mineralogy of Rhyolite
Essential minerals - these are minerals that are required within the classification of this rock:
| Feldspar > Alkali Feldspar | A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium. |
| Feldspar > Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| Silica > Quartz | SiO2 |
Pronunciation of Rhyolite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Age distribution
Recorded ages:
Neoproterozoic to Quaternary : 771 ± 2 Ma to 0.5 ± 0.15 Ma - based on 11 recorded ages.
Synonyms of Rhyolite
Other Language Names for Rhyolite
Irish Gaelic:Rialít
Varieties of Rhyolite
Common Associates
Associated Minerals Based on Photo Data:
| 54 photos of Rhyolite associated with Quartz | SiO2 |
| 36 photos of Rhyolite associated with Topaz | Al2(SiO4)(F,OH)2 |
| 30 photos of Rhyolite associated with Hematite | Fe2O3 |
| 25 photos of Rhyolite associated with Sanidine | K(AlSi3O8) |
| 22 photos of Rhyolite associated with Red Beryl | Be3Al2Si6O18 |
| 19 photos of Rhyolite associated with Bixbyite-(Mn) | Mn3+2O3 |
| 14 photos of Rhyolite associated with Phlogopite | KMg3(AlSi3O10)(OH)2 |
| 13 photos of Rhyolite associated with Tridymite | SiO2 |
| 13 photos of Rhyolite associated with Mordenite | (Na2,Ca,K2)4(Al8Si40)O96 · 28H2O |
| 12 photos of Rhyolite associated with Opal | SiO2 · nH2O |
Internet Links for Rhyolite
mindat.org URL:
https://www.mindat.org/min-48451.html
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References for Rhyolite
Reference List:
Mount Hay, Wycarbah, Rockhampton Region, Queensland, Australia