Langite
Mineral Cu4(SO4)(OH)6·2H2O
About it
Small blue to greenish-blue crystals and crusts in oxidized copper ore and on old mine walls, often formed recently. A hydrated cousin of brochantite; Cornwall is a classic source.
- Type
- Mineral
- Group
- Sulfate, basic copper sulfate
- Formula
- Cu4(SO4)(OH)6·2H2O
- Hardness (Mohs)
- 2.5–3
- Specific gravity
- 3.3–3.5
- Streak
- pale blue-green
- Lustre
- vitreous (glassy), silky
- Crystal system
- Monoclinic
- Colours
- blue, greenish blue, sky blue
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in one direction
Typical values: real specimens vary. For more, see mindat.org.