Genthelvite
Mineral Zn4Be3(SiO4)3S
About it
The zinc member of the helvine group, in pink to green tetrahedra; Mont Saint-Hilaire, Quebec, and St. Peters Dome, Colorado, give crystals that glow strong green under UV.
- Type
- Mineral
- Group
- Silicate (tectosilicate), sodalite group
- Formula
- Zn4Be3(SiO4)3S
- Hardness (Mohs)
- 6.5
- Specific gravity
- 3.44–3.7
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Isometric (cubic)
- Colours
- red, pink, yellow, pale green, emerald green
- Transparency
- transparent, translucent
- Cleavage and fracture
- poor octahedral; uneven to conchoidal fracture
- Under UV light
- often intense green under shortwave and longwave UV, with phosphorescence
Typical values: real specimens vary. For more, see mindat.org.