mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: White to milky grey 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: White to milky grey with dark grey or black veins
Luster: Sub-vitreous to earthy

Identified June 8, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in evaporite deposits as a result of the precipitation of boron and calcium from saline water in arid environments. Often found in cauliflower-like nodules.

Uses & applications

Primarily used for decorative carvings, lapidary work, and beads. Highly valued as a base material for dyeing to imitate turquoise or lapis lazuli due to its porous nature.

Geological facts

Named after Henry How, a 19th-century Canadian mineralogist who first described it in Nova Scotia. It is often sold under the trade names White Turquoise or White Buffalo, though it is chemically distinct from turquoise.

Field identification & locations

Identified by its signature grey spider-web veining on a white background and low hardness (can be scratched by a copper coin). Found primarily in Canada (Nova Scotia) and the USA (California).

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