mineral
Howlite
Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)
Hardness: 3.5; Color: White to milky gray with dark gray/black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None; Specific gravity: 2.53-2.59
- Hardness
- 3
- Color
- White to milky gray with dark gray/black veining
- Luster
- Sub-vitreous to pearly
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Physical properties
Hardness: 3.5; Color: White to milky gray with dark gray/black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None; Specific gravity: 2.53-2.59
Formation & geological history
Formed in evaporite deposits within sedimentary basins, typically associated with gypsum and borax formations. Most common in arid environments.
Uses & applications
Primarily used for decorative carvings, beads, and jewelry. It is frequently dyed blue to imitate turquoise or red to imitate coral.
Geological facts
Howlite was discovered in 1868 near Windsor, Nova Scotia, by Henry How, a Canadian mineralogist. In its natural white state, it is often called 'White Buffalo' or 'White Turquoise' by marketers, though it is unrelated to turquoise.
Field identification & locations
Identify by its characteristic 'spider web' veining and porous surface. It can be found in Nova Scotia, California, and Turkey. Collectors should check for dye by using a cotton swab with acetone on the surface.
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