Danburite
Mineral CaB2Si2O8
About it
Clear prisms with wedge-shaped ends like topaz but with no easy cleavage; Charcas, Mexico, and Dalnegorsk, Russia, give fine groups. Named for Danbury, Connecticut.
- Type
- Mineral
- Group
- Silicate (tectosilicate), danburite group
- Formula
- CaB2Si2O8
- Hardness (Mohs)
- 7–7.5
- Specific gravity
- 2.97–3.02
- Streak
- white
- Lustre
- vitreous (glassy), greasy
- Crystal system
- Orthorhombic
- Colours
- colourless, white, pale yellow, pink, grey
- Transparency
- transparent, translucent
- Cleavage and fracture
- very poor; uneven to conchoidal fracture
- Under UV light
- sometimes sky blue under longwave UV
Typical values: real specimens vary. For more, see mindat.org.