mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Chalky white to milky white with dark grey or black veins; Luster: Sub-vitreous to earthy; Crystal Structure: Monoclinic; Cleavage: None; Specific Gravity: 2.53-2.59

Hardness: 3
Color: Chalky white to milky white with dark grey or black veins
Luster: Sub-vitreous to earthy

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits, usually as nodules in sedimentary basins. It is often found in association with other borate minerals. Most deposits are found in arid climates where water evaporates, leaving behind concentrated minerals.

Uses & applications

Used primarily for decorative carvings, jewelry (as beads or cabochons), and lapidary work. It is highly porous and frequently dyed blue to imitate turquoise or red to imitate coral.

Geological facts

Howlite was first discovered in 1868 by Henry How near Windsor, Nova Scotia. Because of its white color and spiderweb-like veining, it is often marketed under trade names like 'White Turquoise' or 'White Buffalo Stone,' though it is not related to turquoise.

Field identification & locations

Identified in the field by its porcelain-like appearance and chaotic dark veining. It is much softer than quartz or turquoise. Major sources include California and Nevada in the USA, and parts of Canada and Turkey.

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