Trachyte
A rock classification type
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About Trachyte
Name:
Etymol: Greek trachys, rough, in reference to the fact that rocks of this group are commonly rough to the touch.
Trachytic rocks, with felsics comprising 0-5% quartz and alkali feldspar/total feldspar: 0.65-0.9
A group of fine-grained, generally porphyritic, extrusive rocks having alkali feldspar and minor mafic minerals (biotite, hornblende, or pyroxene) as the main components, and possibly a small amount of sodic plagioclase; also, any member of that group; the extrusive equivalent of syenite. Trachyte grades into latite as the alkali feldspar content decreases, and into rhyolite with an increase in quartz.
Ref: AGI
A group of fine-grained, generally porphyritic, extrusive rocks having alkali feldspar and minor mafic minerals (biotite, hornblende, or pyroxene) as the main components, and possibly a small amount of sodic plagioclase; also, any member of that group; the extrusive equivalent of syenite. Trachyte grades into latite as the alkali feldspar content decreases, and into rhyolite with an increase in quartz.
Ref: AGI
Unique Identifiers
Mindat ID:
48478
Long-form identifier:
mindat:1:1:48478:5
Classification of Trachyte
Trachyte appears in field 7 in the QAPF diagram.
Trachyte is found in field T in the TAS diagram.
Sub-divisions of Trachyte
- Trachyte
Mineralogy of Trachyte
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 |
Age distribution
Recorded ages:
Neoproterozoic to Quaternary : 832 ± 40 Ma to 0.01143 Ma - based on 45 recorded ages.
Other Language Names for Trachyte
Portuguese:Traquito
Common Associates
Associated Minerals Based on Photo Data:
| 2 photos of Trachyte associated with Basalt | |
| 1 photo of Trachyte associated with Klockmannite | CuSe |
| 1 photo of Trachyte associated with Clausthalite | PbSe |
| 1 photo of Trachyte associated with Malachite | Cu2(CO3)(OH)2 |
| 1 photo of Trachyte associated with Cobaltomenite | CoSeO3 · 2H2O |
Internet Links for Trachyte
mindat.org URL:
https://www.mindat.org/min-48478.html
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References for Trachyte
Localities for Trachyte
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.
Waitakere River, Waitakere Ranges, Auckland Region, New Zealand