Identity

Formula NaCa4(Si27Al9)O72·28H2O
Class Silicates
Subclass Tectosilicates
Crystal System Monoclinic
Hardness 3.5-4
Color White, peach, salmon pink, brown
Lustre Vitreous to pearly
Specific Gravity 2.15
Cleavage Perfect {010}
Streak White
Technical notes (click to open)(click to close)
Identity The calcium-dominant member of the stilbite zeolite series
Name From the Greek for shine, after its pearly luster
Diagnostic Sheaf-like and bowtie-shaped crystal bundles
Series Stilbite-Ca (common) and stilbite-Na (rare)
Occurrence In basalt cavities with other zeolites

Name & Human History

Etymology

Stilbite is a graceful zeolite, a light, water bearing silicate, usually white, peach, or salmon pink. Its name comes from a Greek word for shine, after the pearly luster of its surfaces. Its most charming feature is its shape. The crystals grow together in sheaves and bundles, often pinched in the middle like a tied bow or a bundle of wheat.

Today

Stilbite is a favorite of collectors for its warm color and elegant form. Peach and salmon colored sheaves of stilbite, often on a bed of other zeolites, make some of the most popular zeolite specimens of all. It has no industrial use to speak of, but few minerals are so pleasing to the eye, which is reason enough to prize it.

Geology & Occurrence

Formation

Stilbite forms in the gas pockets of old lava flows, the home of many zeolites. As mineral rich water moves through cooling basalt, it fills the empty bubbles with crystals. Stilbite grows there alongside other zeolites, as well as calcite and quartz. It also turns up in the cavities of granite and in hot spring deposits.

Notable Localities

Stilbite is found in basalt regions around the world. The great lava flows of India, near Mumbai and Pune, are famous for superb peach colored sheaves. Iceland, Scotland, and the Bay of Fundy in Nova Scotia are classic sources. Fine stilbite also comes from Brazil and the United States.

Did you know?

Stilbite is known by its bow tie shape above all. The crystals fan out from a narrow waist into two flaring ends, like a bundle of straw tied in the middle, or a bow tie. This habit is so distinctive that a collector can often name stilbite at a glance. The full name stilbite-Ca marks the common, calcium rich kind of this lovely zeolite.

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