Aragonite
Mineral CaCO3
About it
Fizzes in acid like calcite but is harder and denser, with no rhomb cleavage. Six-sided twinned clusters come from Morocco and Spain, and coral-like flos ferri from Austria's Erzberg.
- Type
- Mineral
- Group
- Carbonate, aragonite group
- Formula
- CaCO3
- Hardness (Mohs)
- 3.5–4
- Specific gravity
- 2.94–2.95
- Streak
- white
- Lustre
- vitreous (glassy), resinous
- Crystal system
- Orthorhombic
- Colours
- colourless, white, grey, yellow, blue, green, violet, brown
- Transparency
- transparent, translucent
- Cleavage and fracture
- distinct in one direction; subconchoidal fracture
- Under UV light
- sometimes yellow, green, or white under UV
Typical values: real specimens vary. For more, see mindat.org.