Willemite
Mineral Zn2SiO4
Also called Troostite
About it
A zinc ore famous at Franklin and Sterling Hill, New Jersey, where it glows vivid green under shortwave UV beside red-glowing calcite.
- Type
- Mineral
- Group
- Silicate (nesosilicate), phenakite group
- Formula
- Zn2SiO4
- Hardness (Mohs)
- 5.5
- Specific gravity
- 3.89–4.19
- Streak
- white
- Lustre
- vitreous (glassy), resinous
- Crystal system
- Trigonal
- Colours
- green, white, yellow, brown, red, black
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- good basal
- Under UV light
- bright green under shortwave UV, often phosphorescent
Typical values: real specimens vary. For more, see mindat.org.