Howlite
Howlite (Silicoborocalcite) · Semi-Precious Gemstone / Decorative Mineral Specimen
Crystal System
Monoclinic; typically found in massive, nodular, or cauliflower-like habits; rarely occurs as distinct crystals.
Mineral Group
Borates (specifically a Nesoborate/Silicoborate)
Chemical Formula
Ca2B5SiO9(OH)5
Formation Process
Sedimentary formation through chemical precipitation in evaporate basins, often associated with gypsum, anhydrite, and colemanite in arid environments.
About This Crystal
An opaque, milky white to greyish-white stone. It has a sub-glassy to earthy luster and is frequently marked by dark grey, black, or brown erratic veins (matrix) that resemble a spiderweb pattern.
Physical Characteristics
Color: White/Grey; Streak: White; Cleavage: None (massive form); Fracture: Conchoidal to even; Specific Gravity: 2.45-2.58; Luster: Sub-vitreous to earthy; Fluorescence: Sometimes fluoresces brownish-yellow or orange under shortwave UV.
Optical Properties
Opaque; Refractive Index: 1.583–1.605; Birefringence: 0.022 (not observable in massive specimens); no pleochroism due to opacity.
Hardness & Durability
Origin Region
Nova Scotia, Canada (type locality); California and Nevada, USA; Turkey; and Mexico. Found in evaporite basins and continental saline lakes.
Hardness & Durability
Mohs Hardness: 3.5; Toughness: Fairly brittle; low durability for high-impact jewelry like rings; best suited for earrings or necklaces with protective settings.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic cleaners and steam. Extremely sensitive to acids and harsh chemicals. Porous nature allows it to absorb oils or dyes.
Rarity & Value
Common and affordable. Value is determined by the aesthetic of the veining. It is very frequently dyed blue to imitate turquoise ("Turquenite") or red to imitate coral.
Special Characteristics
Highly porous structure makes it an ideal medium for dyeing. Its resemblance to White Turquoise is a common marketing confusion.
Lore & History
Discovered in 1868 by Henry How in Nova Scotia. In metaphysical traditions, it is known as the 'calming stone,' associated with the Crown Chakra and believed to aid in patience and insomnia reduction.