Variscite

Object/Artifact

-

Crater Rock Museum

Variscite

Variscite

Name/Title

Variscite

Entry/Object ID

78.59.859 (a)

Description

Chemical Composition: AlPO4-2H2O Crystal System: Orthorhombic System Description: Common Name: Variscite Chemistry: AlPO4-2H2O, Hydrated Aluminum Phosphate Group: Phosphates Location: Fairfield, Utah Description: Polished side shows varying amounts of bright green variscite with gray and creamy 'eyes' in gray, pale olive, and brown rock. Contains some dark green crystalline filler, with open holes and some light gray crystals along one edge. PHYSICAL CHARACTERISTICS: Color is light green to emerald green, sometimes bluish-green or colorless. Luster is vitreous or waxy. Transparency specimens are translucent. Crystal System is orthorhombic; 2/m2/m2/m Crystal Habits include nodules, fine grain masses, and crusts. Cleavage is normally not applicable, but should be good in one direction, poor in another Fracture is conchoidal, splintery, uneven. Hardness is variable from 3.5 - 5 Specific Gravity is approximately 2.57 (average) Streak is white. Associated Minerals are apatite, limonite, chalcedony, crandallite, wardite and other secondary phosphate minerals. Other Characteristics: alteration to other phosphate minerals causes a shrinkage, yielding gaps between variscite and these other minerals. Best Field Indicators are color, habit, associations, density and luster. Fracture: conchoidal Hardness: 4 Fluorite Luster: Vitreous Occurrence: Variscite is a secondary mineral formed by direct deposition from phosphate-bearing water that has reacted with aluminium-rich rocks in a near-surface environment. It occurs as fine-grained masses in nodules, cavity fillings, and crusts. Variscite often contains white veins of the calcium aluminium phosphate mineral crandallite. Rock Type: Sedimentary Specific Gravity: 2.57 Streak: white Texture: Mircocrystalline Variety: Variscite is a relatively rare phosphate mineral that is sometimes confused with turquoise. It is usually greener, however, than turquoise. Variscite is sometimes used as a semi-precious stone and can make distinctive color patterns that are very attractive. Occassionally it is altered into other phosphate minerals. This can occur in what were perhaps weak layers of a nodule since only portions of the variscite nodules are altered. The most common alteration mineral is crandallite, CaAl3(PO4)2(OH)5-H2O, and gives some nodules a yellow or white layer.

Collection

Tom Riley Variscite Collection

Acquisition

Accession

78.59.

Dimensions

Width

6-1/4 in

Length

4-3/8 in

Dimension Notes

Dimension taken at widest points

Location

Location

Shelf

Right, Right

Building

Mentzer Hall "Caps Collectables"

Category

Permanent

Moved By

Rawley Wyatt

Date

March 24, 2015

Location

Container

Center

Drawer

Top Shelf

Shelf

Right, Right

Wall

West

Building

Mentzer Hall "Caps Collectables"

Category

Permanent

Moved By

Steve Miller

Date

March 31, 2011

Location

Shelf

Right

Cabinet

Case #2

Building

Mentzer Hall "Caps Collectables"

Category

Permanent