Aphanite
Aphanites (adj. aphanitic; from
amorphous), and having a glass-like appearance.[3]
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass, or matrix. The larger inclusions are called phenocrysts. They consist essentially of very small crystals of minerals such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.[2]
Common rocks that can be aphanitic
References
- ^ Le Maitre, R. W., ed. (1989). A classification of igneous rocks and glossary of terms. Oxford: Blackwell Science.
- ^ a b public domain: Chisholm, Hugh, ed. (1911). "Aphanite". Encyclopædia Britannica. Vol. 2 (11th ed.). Cambridge University Press. p. 163. One or more of the preceding sentences incorporates text from a publication now in the
- American Geological Institute.