Calcite (Dogtooth Spar)
Calcite (Mineral Class: Carbonate) · Mineral Specimen / Decorative Stone
Crystal System
Trigonal System; Hexagonal Scalenohedral habit known as "Dogtooth Spar"
Mineral Group
Carbonates; Calcite Group
Chemical Formula
CaCO3 (Calcium Carbonate) with possible iron or manganese trace inclusions
Formation Process
Hydrothermal or Sedimentary; typically forms from the precipitation of calcium-rich fluids in cavities, fractures, or caverns at relatively low temperatures.
About This Crystal
White to creamy-off-white translucent crystal exhibiting a sharp, elongated pyramidal habit. The luster is vitreous (glassy) to pearly on cleavage planes. The surface shows some brownish iron-oxide staining or matrix attachment.
Physical Characteristics
Color: White/Tan; Streak: White; Cleavage: Perfect rhombohedral in three directions (though obscured by the crystal faces here); Fracture: Conchoidal to uneven; Specific Gravity: 2.71; Fluorescence: Often fluoresces red, white, or yellow under UV light.
Optical Properties
Refractive Index: 1.486 - 1.658; Birefringence: Extremely high (0.172), often resulting in double refraction (doubling of images viewed through clear specimens).
Hardness & Durability
Origin Region
Found globally; notable deposits in Joplin, Missouri (USA), Mexico, and the United Kingdom. Often found in limestone caves and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 3.0 (Soft); Toughness: Poor due to easy cleavage; Stability: Sensitive to acids and may be damaged by high heat.
Care & Maintenance
Clean only with warm, soapy water; avoid all acids (including vinegar) which will dissolve the stone. Store away from harder stones like quartz to prevent scratching.
Rarity & Value
Common mineral; value for this specimen is modest, primarily as a collector's mineral specimen. Value increases with size, clarity, and perfection of the crystal terminations.
Special Characteristics
Effervesces (fizzes) strongly when in contact with dilute hydrochloric acid. Shows strong double refraction in transparent varieties (Iceland Spar).
Lore & History
Historically used as a flux in metal smelting and in the production of cement. In metaphysical traditions, calcite is believed to be a powerful amplifier and cleanser of energy, often associated with the Crown and Solar Plexus chakras.