mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Chalky white to milky white with grey or black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None visible in massive form; Specific gravity: 2.53-2.59

Hardness: 3
Color: Chalky white to milky white with grey or black veining
Luster: Sub-vitreous to pearly

Identified July 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits, usually as nodules in sedimentary environments where boron-rich fluids interact with calcium-rich sediments. Found in arid regions where ancient lake beds have evaporated.

Uses & applications

Used primarily in jewelry as beads and decorative carvings. It is very porous and is frequently dyed blue to imitate turquoise or red to imitate coral. Also used as a source of borax.

Geological facts

Howlite was first discovered in 1868 near Windsor, Nova Scotia, by Canadian mineralogist Henry How. Because of its white color and dark veins, it is often nicknamed 'White Buffalo Stone' or 'Snow Leopard Stone' when marketed in jewelry.

Field identification & locations

Identify by its white, porcelain-like appearance and characteristic 'spider web' grey veining. It is much softer than quartz or turquoise. Notable deposits exist in California and Nevada, USA, and Nova Scotia, Canada.

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