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The Mineral scolecite

Colorless Scolecite Spray

Scolecite is a member of the zeolite group, and is closely related to Natrolite and Mesolite. It forms a series with those two minerals, and is the calcium-rich end member. Chemical analysis or optical tests may be required to distinguish Scolecite from Natrolite, and a single crystal may even contain part of each mineral within different zones of the same crystal.

Scolecite can be very brittle, so care should be exercised when handling specimens. Scolecite is named after the Greek term "skolec", which means "worm", alluding to its worm-like reaction to a blowpipe test.

Chemical Formula

CaAl₂Si₃O₁₀ · 3H₂O

Color

White, colorless, light yellow, light pink. Rarely orange.

Crystal System

Monoclinic

Properties

Streak
Colorless

Hardness
5 - 5.5

Transparency
Transparent to translucent

Specific Gravity
2.2 - 2.4

Luster
Vitreous, silky

Cleavage
1,2

Fracture
Uneven

Tenacity
Brittle

Crystal Habits

Most often in acicular and radial groupings, with individual slender crystals clearly distinguished. Individual crystals in an aggregate may be grouped tightly together, or there may be a space between each crystals. Individual prismatic crystals are very rare. Commonly in tall columnar bundles of prismatic crystals. Also in reticulated groups, V-shaped twins, in grainy masses of slender crystals, tight radiating masses, and as linings of cavities.

Additional Information

Composition
Hydrous calcium aluminum silicate

In Group
Silicates; Tectosilicates; Zeolite Group

Striking Features
Crystal habits and environment

Environment
In cavities of volcanic basalt; rarely in granites and gneiss.

Rock Type
Igneous

Uses

Scolecite specimens are of interest to collectors, especially those specializing in zeolite minerals.

Noteworthy Localities

India is the most important producer of Scolecite, where excellent specimens are found in the basalts of the Deccan Traps in the state of Maharashtra. The districts that have produced excellent Scolecite include Nasik, Pune (Poona), Ahmadnagar, Jalgaon, and Mumbai. A recent outstanding find of large radiating clusters associated with Stilbite is Rankhamb, Maharashtra, India.

Other worldwide localities include the Das Antas tunnel, Veranópolis, Rio Grande Do Sul, Brazil; Teigarhorn, Berufjördur, Iceland; Arvigo, Grisons, Switzerland; and several deposits in the Ossola Valley, Piedmont, Italy. In the U.S., Scolecite come from Elk Mountain, northeast of Pigeon Springs, Cowlitz Co., Washington.