Yellow Calcite

Yellow calcite is a descriptive name for natural calcite (calcium carbonate, CaCO₃) in pale to dark yellow shades; it is a colour variety, not a separate mineral species. The cause of the yellow colour is not settled: a 2026 study of yellow calcite from Inner Mongolia attributed it to weak impurity- and defect-related absorption rather than to a dominant iron chromophore. The Japanese retailer Pascle notes that there is no fixed boundary between yellow and orange calcite in the trade.

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Full material guide
Material facts

What the material is, where it comes from or how it is made, identification and care, from the cited sources.

Properties

Material type Natural mineral (colour variety of calcite)
Mineral species Calcite
Chemical formula CaCO₃
Color Pale to dark yellow; honey-coloured material is also called honey calcite
Cause of color Not settled; in studied Inner Mongolia samples, weak impurity- and defect-related absorption (enriched in Mg and rare earth elements such as Y and Ce)
Crystal system Trigonal
Mohs hardness 3
Specific gravity 2.71 (pure) to 2.94
Refractive index 1.486 to 1.658
Birefringence 0.172 to 0.190
Cleavage Perfect rhombohedral, in three directions
Luster Vitreous to pearly
Possible treatments Dyeing, wax or plastic impregnation, irradiation

Origins & sources

Calcite occurs in most geological settings and is most common as massive material in limestone and marble; it also forms in hydrothermal deposits. The yellow calcite studied in 2026 came from the Huanggangliang mining area in Inner Mongolia, China. Gem-quality pale yellow to yellow calcite has also been recorded from the former USSR and from Bancroft, Ontario, Canada. Mindat notes that honey-coloured calcite is widespread in limestone areas.

Identification

Like all calcite, it has a Mohs hardness of 3, three directions of perfect rhombohedral cleavage and very strong birefringence (about 0.172), and it fizzes readily in acids, even weak ones such as vinegar. It can resemble yellow to orange aragonite, a polymorph with the same formula; the Japanese retailer Pascle says the two cannot be told apart by eye. Aragonite is orthorhombic, denser (specific gravity about 2.95 against about 2.71) and has one distinct cleavage instead of three perfect rhombohedral ones. Yellow calcite from Inner Mongolia showed blue-white fluorescence with a short-lived green afterglow under long-wave UV. Calcite may be dyed, impregnated with wax or plastic, or irradiated, so a strong colour in inexpensive beads is not by itself proof of natural colour.

Care

Calcite (Mohs 3) scratches easily and splits readily along its cleavage. A care table based on GIA's Gem Reference Guide advises never using ultrasonic or steam cleaners; warm soapy water is usually safe. Keep it away from acids, which make it effervesce, and from high heat, at which it can crack apart (decrepitate). The same table lists natural calcite colours as stable to light.

History & culture

History

The mineral name calcite comes from the Latin calx, "lime". Mindat describes it as an ancient name and credits Pliny the Elder (AD 79) with naming it as a mineral. Colour names such as this one are descriptive trade names, not separate mineral names.

Cultural meanings

The Japanese retailer Pascle writes that stones of the calcite group are said to settle unstable emotions and smooth relationships with other people, and recommends yellow calcite as a charm for communication.

Traditional beliefs

Not collected yet

Sources

Collected Oct 23, 2026