Garnet var. Almandine

Object/Artifact

-

Crater Rock Museum

Name/Title

Garnet var. Almandine

Entry/Object ID

2009.62.228

Description

Description: Common Name: Garnet (Almandine) Chemistry: Fe3Al2(SiO4)3, Iron Aluminum Silicate Group: Garnet Location: Unknown Description: Deep violet red small (1/4") to large (1 1/2") crystals with translucent white crystals on metamorphic rock matrix. PHYSICAL CHARACTERISTICS: Color is typically red to brown, sometimes with a tinge of purple and sometimes a deep enough red to appear black. Luster is vitreous. Transparency crystals are transparent to translucent. Crystal System is isometric; 4/m bar 3 2/m Crystal Habits include the typical rhombic dodecahedron. also seen is the 24 sided trapezohedron. Combinations of these forms are common and sometimes the rare faces of the hexoctahedron, a 48 sided crystal habit that rarely is seen by itself, can also combine with these other forms making very attractive, complex and multifaceted crystals. Massive occurrences are also common. Crystals typically embedded and isolated, from other alamadine crystals, in metamorphic rocks. Cleavage is absent. Fracture is conchoidal. Hardness is 6.5 - 7.5 Specific Gravity is approximately 4.3 (above average for translucent minerals and the highest density of all garnets) Streak is white. Associated Minerals are micas, staurolite, quartz and feldspars. Other Characteristics: index of refraction is 1.83 and multiplicity of faces give a striated appearance on some crystals. Best Field Indicators are crystal habit, color, density and hardness.

Collection

RAGM Mineral Collection

Dimensions

Width

3 in

Depth

3 in

Length

4 in

Location

Location

Display Case

FS-4

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Date

August 18, 2023