Limestone
Rock
About it
Rock made mostly of calcite, often from shells and skeletons, that fizzes in cold dilute acid and is scratched by a knife. Builds reefs, karst, and caves; Indiana limestone and Tyndall stone of Manitoba are classic building stones.
- Type
- Rock (sedimentary)
- Group
- Sedimentary (biochemical)
- Hardness (Mohs)
- 3–4
- Specific gravity
- 2.3–2.7
- Lustre
- dull
- Colours
- white, grey, cream, tan, buff, black
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.