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The Mineral wavellite

Concentric Radial Wavellite

Wavellite is a classic radiating mineral, forming spectacular pinwheel aggregates emanating from a central core in spherulitic balls. When the balls are complete, the radial structure is internal and not usually visible. A crystal aggregate needs to be fractured to see and appreciate the outstanding radial habit of Wavellite. Wavellite was named in 1805 after William Wavell, an English physician who first discovered this mineral.

Chemical Formula

Al₃(PO₄)₂(OH)₃ · 5(H₂O)

Color

Light to dark green, yellowish-green, yellow, brown, gray. Rarely white or colorless. May exhibit concentric multicolored zoning in radial cross-sections.

Crystal System

Orthorhombic

Properties

Streak
White

Hardness
3.5 - 4

Transparency
Transparent to opaque

Specific Gravity
2.3 - 2.4

Luster
Vitreous, pearly

Cleavage
1,1;2,2

Fracture
Uneven

Tenacity
Brittle

Crystal Habits

Single crystals, which are long prismatic and usually striated, are rare. Most often in radial and radiating aggregates, and in rounded, ball-shaped clusters of spherulitic masses. Also botryoidal, stalactitic, and acicular.

Additional Information

Composition
Aluminum phosphate, sometimes with some iron and fluorine

In Group
Phosphates; True Phosphates

Striking Features
Crystal aggregate habits and mode of occurrence.

Environment
As a secondary mineral in the oxidation zone of low-grade metamorphic rocks, epithermal veins, and in phosphate-rich sedimentary deposits.

Rock Type
Sedimentary, Metamorphic

Uses

Wavellite is mainly used as a collectors mineral.

Noteworthy Localities

Large and lustrous, cream to yellowish Wavellite comes from the Siglo Veinte Mine, Llallagua, Potosí Department, Bolivia. Good European localities include the Lichtenberg Mine, Ronneburg, Thuringia, Germany; the High Down Quarry, Filleigh, North Devon, England; and the Laharran Quarry, Tracton, Ireland.

The most important occurrences of this mineral are in Arkansas, with several different localities producing the most outstanding forms of Wavellite. The specific localities include Dug Hill, Avant, Garland Co.; Mauldin Mt., Montgomery Co.; Mt. Ida, Montgomery Co.; and Hot Springs, Garland Co.

Large and bright yellow and green Wavellite spheres are found in the National Limestone Quarry, Mount Pleasant Mills, Snyder Co., Pennsylvania; and a deep green form comes from Slate Mountain, El Dorado Co., California.