| 释义 |
- Common rocks that can be aphanitic
- References
{{short description|Igneous rocks which are so fine-grained that their component mineral crystals are not detectable by the unaided eye}}Aphanite, or aphanitic as an adjective (from the Greek αφανης, "invisible"), is a name given to certain igneous rocks that are so fine-grained that their component mineral crystals are not detectable by the unaided eye[1] (as opposed to phaneritic igneous rocks, where the minerals are visible to the unaided eye). This geological texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments. As a rule, the texture of these rocks is not the same as that of volcanic glass (e.g., obsidian), with volcanic glass being non-crystalline (amorphous), and having a glass-like appearance.[2]Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass or matrix. The large inclusions are called phenocrysts. They consist essentially of very fine-grained minerals, such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.[1] Common rocks that can be aphanitic- Andesite
- Basalt
- Basanite
- Dacite
- Felsite
- Phonolite
- Rhyolite
- Trachyte
References1. ^1 {{EB1911|inline=y|wstitle=Aphanite|volume=2|page=163}}
2. ^Bates and Jackson, 1984, Dictionary of Geological Terms, 3rd ed., Prepared by the American Geological Institute
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