Howlite

Infobox mineral
name = Howlite
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formula = Ca₂B₅SiO₉(OH)₅
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color = white/gray/black
habit = nodules
system = monoclinic
twinning =
cleavage = absent
fracture = conchoidal, uneven
mohs = 3.5
luster = vitreous to dull
refractive = opaque to translucent
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streak = gray to black
gravity = 2.5+
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Howlite, a calcium borosilicate hydroxide (Ca₂B₅SiO₉(OH)₅), is a silicate found in evaporite deposites. [ [http://www.galleries.com/minerals/silicate/howlite/howlite.htm Howlite] at Mineral Galleries ] Howlite was discovered at Tick Canyon, California in 1868 by Henry How (1828 - 1879), a Canadian chemist, geologist, and mineralogist.

In appearance, it is white with fine grey or black veins in an erratic, often web-like pattern, and is opaque with a sub-vitreous lustre. Its structure is monoclinic with a Mohs hardness of 3.5 and lacks regular cleavage..

Howlite is commonly used to make decorative objects such as small carvings or jewelry components. Because of its porous texture, howlite can be easily dyed to imitate other minerals, especially turquoise because of the superficial similarity of the veining patterns. Howlite is also sold in its natural state, sometimes under the misleading trade names of "white turquoise" or "white buffalo turquoise", or the derived name "white buffalo stone".

References

* [http://webmineral.com/data/Howlite.shtml Webmineral]
* [http://www.mindat.org/min-1936.html Mindat]