mineral

Howlite

Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Chalky white to milky white with grey or black spider-web veins; Luster: Sub-vitreous to pearly or earthy; Crystal structure: Monoclinic (though rarely found as crystals); Cleavage: None/Indistinct; Specific gravity: 2.45 - 2.58.

Hardness: 3
Luster: Sub-vitreous to pearly or earthy

Identified March 28, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is an evaporite mineral found in continental evaporite deposits, typically occurring as nodules in sedimentary environments. It was first discovered in 1868 by Henry How in Nova Scotia, Canada.

Uses & applications

Used primarily for decorative objects, beads, and jewelry. Because of its porous nature, it is frequently dyed blue to imitate turquoise (sometimes called 'Turquenite') or red to imitate coral.

Geological facts

Howlite is often called the 'imitation stone' because it can be dyed almost any color. It is naturally very soft, often requiring a protective coating if used in high-wear jewelry like rings.

Field identification & locations

Identify in the field by its distinctive 'cauliflower' nodule shape and dark spider-web veining. It is commonly found in Nova Scotia (Canada), California (USA), and parts of Turkey. Collectors look for pieces with high-contrast veining.

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