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The Mineral clinozoisite

Gemmy Clinozoisite from Pakistan

Clinozoisite is the same as Zoisite but crystallizes in the monoclinic system, which scientifically classifies it as an individual mineral species. Clinozoisite is also almost identical in composition to Epidote but lacks significant iron in its structure. It forms a series with Epidote, and in many cases the actual distinction between these two minerals cannot be made. In fact, some specimens from certain localities are labeled as Clinozoisite-Epidote since they are intermediary between these two minerals without an exact determination.

Clinozoisite is named after its monoclinic crystal habit and the reference to its polymorph Zoisite.

Chemical Formula

Ca2Al3(SiO4)3(OH)

Color

Brown, brownish-green, olive-green, greenish yellow, dark yellow, gray, beige. Rarely pink or white.

Crystal System

Monoclinic

Properties

Streak
White
Hardness
7
Transparency
Transparent to translucent
Specific Gravity
3.2 - 3.4
Luster
Vitreous
Cleavage
1,1
Fracture
Uneven
Tenacity
Brittle

Crystal Habits

In prismatic or elongated crystals, in columnar groups, and in short stubby crystals and crystal groups. Crystals may be striated lengthwise. Also reticulated, radiating, acicular, in veins, and massive.

Additional Information

Composition
Basic calcium aluminum silicate, occasionally with small amounts of iron.
In Group
Silicates; Sorosilicates
Striking Features
Color, cleavage, and environment
Environment
In hornfels and skarns in contact metamorphic rocks, as well as in metamorphosed limestones. Also in schists in regional metamorphic rock.
Rock Type
Metamorphic

Varieties

 -   Pink, manganese-rich variety of Clinozoisite, that is very similar and often confused with the pink Thulite variety of Zoisite.
 -   Rare, strontium-rich member of Clinozoisite with one of the calcium atoms replaced by strontium. It is named after the type locality of Niigata Prefecture, Japan, and is scientifically categorized as an individual mineral species. Niigataite was renamed to Clinozoisite-(Sr) by the IMA in 2006.

Uses

Most forms of Clinozoisite are ugly and do not have much use. The rare transparent forms, especially from Pakistan, make a valuable collectors mineral.

Noteworthy Localities

The best examples of this mineral are from Pakistan in gemmy brown elongated crystals, found in the Tormiq valley and Shigar Valley (Alchuri) in Skardu. Dense olive-green fans and interconnected spikes of Clinozoisite crystals come from the Los Serranos Quarry, Albatera, Spain. Small pink crystals come from the Val D'Ossola, Piedmont, Italy; and stubby golden brown crystals from the Quiruvilca Mine, La Libertad, Peru. Large Clinozoisite crystals came from Real del Castillo, near Ensenada, Baja California Norte, Mexico; and small acicular pink crystal groupings from Alamos, Sonora, Mexico.

In the U.S., the vast majority of Clinozoisite localities are in the Northeast. Good crystals come from Sanford, York Co., Maine; and Joppa Hill, Amherst, Hillsborough Co., New Hampshire. Exceptional transparent crystals come from the Belvidere Mountain quarries, Lowell/Eden, Orleans & Lamoille Cos., Vermont. Other important Clinozoisite localities are Chester, Hampden Co., Massachusetts; Old Mine Plaza, Trumbull, Fairfield Co., Connecticut; West Redding, Fairfield Co., Connecticut; and the Hunting Hill quarry, Rockville, Montgomery Co., Maryland. Large, well-developed crystals came from the Keystone Quarry, Cornog, Chester Co., Pennsylvania; and the pink variety from Spruce Pine, Mitchell Co., North Carolina (where it is often confused with the Thulite variety of Zoisite).

Distingushing Similar Minerals

Epidote - Usually greener in color and slightly higher specific gravity; otherwise difficult to distinguish.
Torumaline - Lacks perfect cleavage.

The pink Clinothulite variety is often confused with the Thulite variety of Zoisite.

clinozoisite Photos



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