mineral

Dyed Magnesite (often sold as Red Turquoise or Howlite)

Magnesium Carbonate (MgCO3)

Hardness: 3.5-4.5 (Mohs scale), Color: Naturally white/grey but dyed red or turquoise in this sample, Luster: Vitreous to dull, Crystal structure: Trigonal, Cleavage: Perfect rhombohedral

Hardness: 3

Identified March 24, 2026More mineral →

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Physical properties

Hardness: 3.5-4.5 (Mohs scale), Color: Naturally white/grey but dyed red or turquoise in this sample, Luster: Vitreous to dull, Crystal structure: Trigonal, Cleavage: Perfect rhombohedral

Formation & geological history

Formed by the alteration of magnesium-rich rocks (serpentine or olivine) during regional metamorphism or by the action of magnesium-bearing solutions on limestone. It is found in deposits ranging from Precambrian to recent geological ages.

Uses & applications

Primary use is industrial (magnesium oxide production, refractory bricks). In jewelry, it is widely used as a cost-effective substitute for coral or turquoise once dyed and stabilized with resin.

Geological facts

Magnesite is extremely porous, allowing it to take dyes very easily. While the specimen in the image mimics 'Red Coral' or 'Red Turquoise,' those colors do not occur naturally in magnesite. It is often structurally indistinguishable from howlite without chemical testing.

Field identification & locations

Identify in the field by its association with ultramafic rocks. In jewelry form, check for 'spiderweb' matrix lines and perform a dye test (a cotton swab with acetone will often remove the surface color of dyed specimens). Common locations include Brazil, China, and the USA (California/Nevada).

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