Ore Minerals

Physical Properties of Ore Minerals

Electrical, magnetic, crystal structure, and optical properties of polar dielectric sulfide and related ore minerals are given in Table 1 for minerals that fall in cubic crystal class at ordinary temperatures. Table 2 tabulates minerals that fall in the hexagonal subsystem of the hexagonal crystal class, and Table 3 lists minerals in the trigonal subsystem of that crystal class. Monoclinic ore minerals are listed in Table 4, while minerals in the orthorhombic crystal class are given in Table 5. Two triclinic polar dielectric ore minerals are included in Table 7. Individual minerals can be found by name in the index.

Corry (1994) has noted that there are presently about 20 known ferroelectric ore minerals. References for known ferroelectric ore minerals are given in the tables with the mineral. Extended bibliographies for the ferroelectric minerals can be found in Hellwege and Hellwege (1982).

It is also possible to predict other ore minerals that may be ferroelectric by extrapolation from known characteristics. Crystals with the same space group as a known ferroelectric commonly also prove to be ferroelectric. Other characteristics, such as optical anisotropy, known structural phase changes, etc., are also indicative of possible ferroelectricity. Such characteristics for individual minerals are presented in Tables 1 through 7, and can be found by mineral name in the index.

Matthias (1967) pointed out that sulfur has the same high electronic polarizability as oxygen octahedra and the same propensity to form ferroelectric crystals. Thus, sulfides that are isostructural with oxide ferroelectrics may also be ferroelectric. By the same reasoning, telluride (GeTe is a well-known ferroelectric), selenide, and arsenide ore minerals are also considered to be probable or possible ferroelectrics. Sixty-plus ore minerals that are isostructural with known ferroelectric minerals have been tabulated. With twenty known ferroelectric ore minerals and more than sixty minerals isostructural with known ferroelectrics, ferroelectricity should be regarded as a common property of ore minerals.

Known ferroelectric, probable ferroelectric, possible ferroelectric, pyroelectric, and piezoelectric minerals are also indexed. Known magnetic mineral properties such as ferrimagnetic, antiferromagnetic, diamagnetic, and paramagnetic behavior are also indexed.

The following conditions are applicable to the physical properties given in Tables 1 through 7:

Dielectric permittivity, e, is measured in the frequency range 1 kHz to 1 MHz, unless otherwise noted.
Values for resistivity, dielectric permittivity, and magnetic susceptibility are without reference to crystal axes unless otherwise noted.
Where the mineral is thought to be ferroelectric, but the necessary experimental work has not been done, the Curie temperature is assumed to lie within the stability range of the mineral, and is given as < when stated.
Crystal class and space group are given for a nominal temperature of 25°C.
Due to limitations in HTML only the Schoenflies notation is shown for space groups. Complete tables are available showing the Hermann and Mauguin symbols and the point group for these ore minerals.
Where known, the resistivity in ohm-m is given for these ore minerals. High, low, and mean values are included where sufficient measurements have been made.
Surface charges on mineral faces were measured using a FET input digital voltmeter by Corry and Bookstrom (1981, unpublished data) using point contact electrodes.

Additions and corrections to these tables are welcomed.

Abbreviations used in tables
References not cited directly in table
Table 1. - Cubic Crystal Class
Table 2. - Hexagonal Crystal Class - Hexagonal Subystem
Table 3. - Hexagonal Crystal Class - Trigonal Subystem
Table 4. - Monoclinic Crystal Class
Table 5. - Orthorhombic Crystal Class
Table 6. - Tetragonal Crystal Class
Table 7. - Triclinic Crystal Class

Ore Minerals - 29 JAN 1997

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