Howlite
Howlite · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Monoclinic; crystals are extremely rare, usually found in massive, nodules, or cauliflower-like shapes.
Mineral Group
Borates
Chemical Formula
Ca2B5SiO9(OH)5
Formation Process
Sedimentary; forms via chemical precipitation in evaporite basins, often associated with other borate minerals like colemanite and ulexite.
About This Crystal
Tumbled, opaque white to greyish stone featuring a distinctive sub-vitreous to sub-waxy luster. The surface exhibits a network of dark grey to black erratic veining (matrix) that creates a marble-like appearance.
Physical Characteristics
Color is white or light grey with black/brown veining; white streak; no cleavage in massive form; sub-conchoidal to even fracture; specific gravity 2.53-2.59; occasionally shows orange or brownish fluorescence under shortwave UV.
Optical Properties
Opaque; refractive index approximately 1.583-1.605; biaxial negative; no pleochroism or significant dispersion visible in opaque massive forms.
Hardness & Durability
Origin Region
Nova Scotia (Canada), California (USA), and Turkey; typically found in evaporite basins and borate deposits.
Hardness & Durability
Mohs hardness of 3.5; relatively soft and brittle; poor toughness; low durability for rings but suitable for earrings and pendants.
Care & Maintenance
Clean only with warm soapy water and a soft cloth; avoid ultrasonic cleaners, steam, and acidic chemicals; store separately to prevent scratching by harder stones (like quartz).
Rarity & Value
Common; very inexpensive; often dyed blue or green to imitate turquoise or lapis lazuli (known as 'Turquenite' when dyed). Value is based on the attractiveness of the veining.
Special Characteristics
Highly porous nature makes it the primary candidate for dyeing in the gemstone industry; known for its 'cauliflower' nodule growth habit in its raw state.
Lore & History
Discovered in 1868 by Henry How in Nova Scotia. In metaphysical traditions, it is known as the 'Attunement Stone' and is believed to calm the mind, relieve stress, and aid in insomnia (traditional beliefs, not scientific fact).