Dogtooth Calcite
Characteristics
- Habit -
- Form - trigonal
- Hardness - 3
- Cleavage - perfect
- Fracture - Conchoidal
- Streak - white
- Lustre - vitreous, sub-vitreous, resinous, waxy, pearly
- Colour - white, yellow, red, orange, blue, green, brown, gray etc.
Introduction
Calcite is a very common and widespread mineral with highly variable forms and colours. Calcite is best recognized by its relatively low Mohs hardness (3) and its high reactivity with even weak acids, such as vinegar, plus its prominent rhombohedral cleavage in most varieties [the trigonal crystal system is often confused with the rhombohedral lattice system].
Dogtooth Calcite—also called Dogtooth Spar—is a variety of calcite that grows in elongated, scalenohedral crystals. Each crystal looks like a sharply tapered tooth. The edges can be razor-thin, and the faces often shimmer with a vitreous luster that ranges from glass-clear to honey-amber, smoky brown, snowy white or even soft lilac.
Translucent to transparent; brittle; prolonged light can fade colored varieties; clean - brief rinse is fine, avoid long soaks; cources - Mexico, USA (Tennessee, Missouri), Spain, Romania, South Africa; CaCO₃.
Dogtooth Calcite usually grows in limestone caves, veins, fractures or geodes where calcium-rich groundwater lingers. Over hundreds or thousands of years, each drop deposits a microscopic layer of calcium carbonate. Slowly, those layers stack into pointed prisms that can reach fist-sized proportions. In some localities, thin coatings of barite, fluorite or quartz add extra sparkle or color zoning, making each specimen one-of-a-kind.
