Millerite
Mineral NiS
Also called Capillary pyrites and Hair pyrites
Take care.
- Fragile: Handle it gently and pack it well; it breaks or crumbles easily.
About it
Brassy, hair-thin needles in radiating sprays, often inside geodes or on calcite. Famous from Keokuk geodes in Iowa, Halls Gap in Kentucky, and the Marbridge mine, Quebec.
- Type
- Mineral
- Group
- Sulfide, millerite group
- Formula
- NiS
- Hardness (Mohs)
- 3–3.5
- Specific gravity
- 5.3–5.5
- Streak
- greenish black
- Lustre
- metallic
- Crystal system
- Trigonal
- Colours
- pale brass yellow, iridescent tarnish
- Transparency
- opaque
- Cleavage and fracture
- perfect rhombohedral; uneven fracture
Typical values: real specimens vary. For more, see mindat.org.