Astrophyllite

Object/Artifact

-

Crater Rock Museum

Astrophyllite

Astrophyllite

Name/Title

Astrophyllite

Entry/Object ID

2014.1.140

Description

Chemical Composition: (K,Na)3(Fe,Mn)7Ti2(SiO3)8 Crystal System: Triclinic System Description: Common Name: Astrophyllite Chemistry: (K,Na)3(Fe,Mn)7Ti2(SiO3)8(O,OH)7, Potassium Sodium Iron Manganese Titanium Silicate Hydroxide. Group: Silicates Location: Russia Description: This is a thin slab of brown and gray mineral with flecks of brassy colored mettalic mineral scattered throughout. It has been polished on one surface. PHYSICAL CHARACTERISTICS: Color is usually golden yellow or yellowish brown, but also greenish brown specimens are found. Luster is vitreous or submetallic to metallic, can be pearly on cleavage surfaces. Transparency: crystals are translucent to opaque. Crystal System is triclinic; bar 1 Crystal Habits include small tabular or bladed crystals often grouped in starlike aggregates. Also found in lamellar massives. Cleavage is perfect in one direction. Fracture is uneven. Hardness is 3. Specific Gravity is 3.3 - 3.4 Streak is yellowish white. Associated Minerals are quartz, feldspars, nepheline, micas and aegirine. Other Characteristics: color is often patchy or heterogenous in distribution. Best Field Indicators brittleness, cleavage, color, luster and localities. Fracture: uneven Hardness: 3 Calcite Luster: Vitreous Occurrence: Found in cavities and fissures in unusual felsic igneous rocks, astrophyllite is associated with feldspar, mica, titanite, zircon, nepheline, and aegirine. Common impurities include magnesium, aluminium, calcium, zirconium, niobium, and tantalum. Rock Type: Metamorphic Specific Gravity: 3.3 - 3.4 Streak: golden Texture: crystaline Variety: Astrophyllite is a rare titanium mineral found in some unusual granites and syenites. It produces a variable luster that can be nearly metallic in one specimen to vitreous in another. Its name translated means star sheets and probably is in allusion to the intergrown starlike aggregates that it can form

Collection

RAGM Mineral Collection

Acquisition

Accession

2014.1

Source or Donor

Crater Rock Museum (unknown donors)

Acquisition Method

Gift

Dimensions

Width

3-1/4 in

Depth

1/4 in

Length

7-1/4 in

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-9

Room

Frieda Smith Hall

Building

Crater Rock Museum

Date

December 29, 2023

Location

Cabinet

J-1 front

Wall

North

Building

Storage (old gift shop upstairs)

Category

Permanent