Herderite

Object/Artifact

-

Crater Rock Museum

Name/Title

Herderite

Entry/Object ID

2009.62.241

Description

Chemical Composition: Phosphates Crystal System: Monoclinic System Description: Common Name: Hydroxyl-Herderite Chemistry: CaBe(PO4)(OH) Class: Phosphates Location: Sao Geraldo Do Baxio, Governador, Valadares, Rio Doce, Minas Gerais, Brazil Description: Physical Characteristics: •Color is colorless, white, yellowish or pale green to blue-green. •Luster is vitreous. •Transparency: Specimens are transparent to translucent. •Crystal System is monoclinic; 2/m •Crystal Habits include prismatic crystals with a complex, but over all domal termination. The prism faces may be rounded and etched. Twinning is common forming cyclic twins that have a malformed hexagonal tabular crystal. The "malformation" usually results in a crystal that looks more orthorhombic than hexagonal and are easily confused with crystals of barite. Other types of twinning can form "fishtail" twins similar to gypsum's famous twins. Also found in nodules, fibrous aggregates, radiating clusters and small grains. •Cleavage is indistinct in two directions (prismatic). •Fracture is subconchoidal. •Hardness is variable from 5 - 5.5 •Specific Gravity is approximately 2.9 - 3.0 (average) •Streak is white. •Other Characteristics: Thermoluminescent, meaning it may glow with a weak blue light upon extreme heating (but this test may damage the specimen). Also sometimes fluorescent, showing deep blue in longwave ultraviolet light. •Associated Minerals include those minerals common to phosphatic grantite pegamtites. •Notable Occurrences include Golconda Mine, Minas Gerais, Brazil; several locations in Germany and Mursinsk, Russia. It the United States there are several locations that produce plentiful supplies of good crystals such as Newry, Stoneham and Topsham, Maine; Fletcher Mine, Alexandria, New Hampshire and San Diego County, California. •Best Field Indicators are crystal habit, color, fluorescence if seen, hardness and localities. Fracture: sub-conchoidal Hardness: 5 Apatite Luster: Vitreous Rock Type: Igneous Specific Gravity: 2.9-3 Streak: White

Collection

RAGM Mineral Collection

Acquisition

Accession

2009.62

Source or Donor

Museum Collection of Minerals

Acquisition Method

Donation

Dimensions

Width

2-1/2 in

Depth

4-1/4 in

Length

3-1/2 in

Location

Location

Display Case

FS-3-A

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Exhibit

Moved By

Jillian Mather Kettley

Notes

Inventory/ location