Andesite
Rock
About it
Grey, fine-grained volcanic rock, often dotted with white plagioclase and black hornblende or pyroxene crystals. Typical of subduction-zone volcanoes; named for the Andes and common in the Cascades.
- Type
- Rock (igneous)
- Group
- Igneous (volcanic)
- Specific gravity
- 2.4–2.8
- Lustre
- dull
- Colours
- grey, dark grey, greenish grey, brown, pinkish
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.