mineral

Howlite

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

AI-generated identification · may be incorrect

Hardness: 3.5 on Mohs scale; Color: Milky white to grey with dark brown or black spider-web veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None (conchoidal fracture); Specific gravity: 2.53-2.59

Hardness: 3
Luster: Sub-vitreous to pearly

Identified March 25, 2026More mineral →

Explore Howlite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in evaporite deposits within sedimentary basins through a hydrothermal process. It typically occurs as nodules or massive irregular cauliflower-like shapes. Deposits can date back to various geological eras depending on the basin formation.

Uses & applications

Used primarily for decorative carvings, jewelry beads, and cabochons. Because of its porous nature, it is frequently dyed blue or green to imitate turquoise (often called 'turquenite').

Geological facts

First discovered in 1868 by Henry How near Windsor, Nova Scotia. It is naturally very soft and porous, making it one of the easiest minerals to dye. It is often sold as 'White Turquoise' in metaphysical shops.

Field identification & locations

Identify by its opaque white color and characteristic erratic web-like veining. Unlike marble, it will not react strongly to acid. Commonly found in California and Canada. Collectors look for pieces with high-contrast veining or well-carved shapes like this crescent moon.