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Large Howlite Nodule

The Mineral howlite




Howlite specimens are often tumbled and polished, then sold to collectors, who find a particular liking to this inexpensive stone. Howlite can be easily dyed, and if dyed a turquoise-blue color it resembles the mineral Turquoise. Howlite is often used as a cheap substitute for Turquoise, and some dishonest dealers label dyed Howlite as Turquoise.

Howlite is named for its discoverer, Henry How, a Nova Scotia geologist.
Chemical Formula Ca2B5SiO9(OH)5
Composition Basic calcium silico-borate
Color White, commonly marked with black or brown intersecting vine-like or skin-like veins
Streak White
Hardness 3.5
Crystal System Monoclinic
Crystal Forms
and Aggregates
Occurs in giant masses and as fragments of them. Also occurs as large and small nodules resembling cauliflower heads. Large masses have the same texture as unglazed porcelain. Crystals, which are tabular, are barely noticeable with the naked eye. They are found in only one region in Nova Scotia, where the crystals occur on large nodules. Also occurs scaly and earthy.
Transparency Translucent in thin splinters; otherwise opaque
Specific Gravity 2.5 - 2.6
Luster Dull, sometimes vitreous
Cleavage None
Fracture Conchoidal to even
Tenacity Brittle
Other ID Marks Sometimes fluorescent cream-yellow to white in shortwave ultraviolet light.
Complex Tests Soluble in hydrochloric acid
In Group Borates; Hydrous Borates
Striking Features Mineral formations and localities
Environment Borax evaporite deposits in dry lakes and in sedimentary clay.
Rock Type Sedimentary
Popularity (1-4) 3
Prevalence (1-3) 2
Demand (1-3) 2

Howlite ON EBAY


USES
The attractive black and brown intersecting veins in Howlite make it useful as an ornamental stone. It is used as gemstone for beads and is often tumbled and sold to amateur collectors. When dyed blue it is used as an inexpensive substitute for Turquoise.

NOTEWORTHY LOCALITIES
Howlite occurs at many evaporation deposits in southern California as huge nodules. Notable areas include Tick Canyon (near Saugus), Lang, Los Angeles Co.; Dagget, San Bernardino Co.; Death Valley, Inyo Co; and Boron, in the Kramer District, San Bernardino Co. It also occurs in Nova Scotia, Canada, in Bras D'Or Lake off Cape Breton Island; and near Windsor, Hants Co. Both these localites are known for their tiny tabular crystals on large nodules, and they are the only occurrences to date where visually crystallized examples of this mineral occur.

Other localities are the Muddy Mountains, Clark Co., Nevada; and the Bigadic Mine, Marmara Region, Turkey.

COMMON MINERAL ASSOCIATIONS
Borax, Ulexite, Colemanite, Anhydrite

DISTINGUISHING SIMILAR MINERALS
Datolite - Greater hardness, found in different mineral environment, often occurs in a greater color variety.
Bakerite - Harder (4½).


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