Gahnite

Object/Artifact

-

Crater Rock Museum

Name/Title

Gahnite

Entry/Object ID

2014.1.60

Description

Chemical Composition: Al(OH)3 Crystal System: Hexagonal System Description: Common Name: Gahnite / Monazite Chemistry: ZnAl2O Group: Oxides Location: San Bernadino,CA Description: Small specimen with reddish-brown and beige matrix and small green crystals throughout. Physical Charateristics: Color is commonly green but also known to be blue, yellow, brown or gray. • Luster is vitreous. • Transparency: Crystals are generally just translucent to almost opaque, but some slightly transparent specimens are known. • Crystal System: Isometric; 4/m bar 3 2/m • Crystal Habits include the typical octahedron, but can be found as dodecahedrons and cubes. Octahedrons may be truncated by dodecahedral faces and commonly show striations parallel to the octahedron-dodecahedron boundary. Twinning by the Spinel Twin Law can produce trigonal appearing crystals with three reentrant angles on the sides of the crystal. • Cleavage: None • Fracture is conchoidal. • Hardness is 7.5 - 8.0 • Specific Gravity is 4.55 - 4.60 • Streak is gray. • Associated Minerals include calcite, spinel, franklinite and several types of garnets. • Notable Occurrences include Rowe and Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine and Franklin New Jersey, USA and Falun, Sweden. • Best Field Indicators are crystal habit, color, hardness, density and locality. Hardness: 7 Quartz Rock Type: Sedimentary

Collection

RAGM Mineral Collection

Acquisition

Accession

2014.1

Source or Donor

Crater Rock Museum (unknown donors)

Acquisition Method

Gift

Dimensions

Height

3 in

Width

1-1/8 in

Length

2-1/4 in

Location

Location

Display Case

FS-11

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Moved By

Curtis Gardner

Date

July 21, 2023