Garnet var Almandine

Object/Artifact

-

Crater Rock Museum

Name/Title

Garnet var Almandine

Entry/Object ID

2009.62.67

Description

Chemical Composition: Fe3 Al2(SiO4)3 Crystal System: Orthorhombic System Description: Common Name: Garnet var Almandine Chemistry: Fe3Al2(SiO4)3, Iron Aluminum Silicate Group: Garnets Location: Otzal Tinol, Austria Description: A very deep dark red garnet crystals individually spaced on a large silvery-gray schist 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. Fracture: conchoidal Hardness: 3 Calcite Luster: Vitreous Occurrence: Found in metamorphic formations primarily schist. Rock Type: Metamorphic Specific Gravity: 2.2 Streak: white Variety: Almandine is the most common of the garnets and is usually the garnet found in garnet schists (a type of metamorphic rock composed mostly of mica).

Collection

RAGM Mineral Collection

Acquisition

Accession

2009.62

Source or Donor

Museum Collection of Minerals

Acquisition Method

Donation

Dimensions

Height

2 in

Width

2-3/4 in

Length

6-1/2 in

Weight

21.58 oz

Dimension Notes

Dimension taken at widest points

Location

Location

Container

Center

Drawer

2nd Shelf

Shelf

Center, Center

Wall

South wall

Room

Delmar Smith Hall

Building

Crater Rock Museum

Category

Permanent

Moved By

Steve Miller

Date

January 15, 2010

Location

Container

Center

Drawer

2nd Shelf

Shelf

Center

Cabinet

Case #43

Wall

South wall

Room

Delmar Smith Hall

Building

Crater Rock Museum

Category

Permanent