Calcareous Tuff (Limestone/Tufa)
Calcium Carbonate (Calcite/Aragonite aggregation) · Mineral Specimen / Sedimentary Rock
Crystal System
Trigonal or Orthorhombic; typically exhibits a massive, porous, or microcrystalline habit lacking visible crystal faces.
Mineral Group
Carbonates
Chemical Formula
CaCO3
Formation Process
Sedimentary/Evaporitic: Formed through the chemical precipitation of calcium carbonate from ambient temperature water bodies or hydrothermal springs.
About This Crystal
An opaque, light-tan to grayish-white porous rock. It features a rugged, granular texture with a dull, earthy luster. The surface is uneven and appears to contain small pits or voids consistent with rapid precipitation.
Physical Characteristics
Color: Creamy white to beige; Streak: White; Cleavage: None (in massive form); Fracture: Irregular/Uneven; Density: 1.9–2.5 g/cm³; Non-fluorescent usually, but may show pale yellow under UV if impurities are present.
Optical Properties
Opaque; No visible pleochroism or dispersion; Lacks optical phenomena due to its microcrystalline/rock-like structure.
Hardness & Durability
Origin Region
Globally distributed; commonly found in limestone-rich regions, around hot springs, or alkaline lake beds.
Hardness & Durability
Mohs hardness: 3; Low durability. It is brittle and can be scratched by a copper coin or steel blade. Highly sensitive to acids.
Care & Maintenance
Keep away from all acids (even vinegar) which causes effervescence. Clean with dry soft brushes only; avoid soaking as it is porous and may absorb contaminants.
Rarity & Value
Common; very low market value as a gemstone. Valued primarily as a geological specimen or for landscaping/industrial use.
Special Characteristics
Porous structure and vigorous effervescence (bubbling) when in contact with dilute hydrochloric acid.
Lore & History
Historically used as a lightweight building material (Tufa). In metaphysical traditions, it is often associated with the Root Chakra and grounding, though these are cultural beliefs rather than scientific facts.