Pitchstone
Rock
About it
Volcanic glass with a dull, resinous lustre like hardened pitch, holding more water than obsidian and often small crystals. Known from the Isle of Arran and the Isle of Eigg in Scotland.
- Type
- Rock (igneous)
- Group
- Igneous (volcanic glass)
- Lustre
- resinous, dull
- Colours
- black, dark green, brown, grey, red
- Transparency
- translucent, opaque
- Cleavage and fracture
- none; conchoidal to uneven fracture
Typical values: real specimens vary. For more, see mindat.org.