Brucite Value, Price, and Jewelry Information

A slightly greenish blue, “sea foam” 0.96-ct brucite, 6.6 x 6.5 mm, square step cut, South Africa. © The Gem Trader. Used with permission.

Brucite

Brucites are extremely difficult to cut. Although too soft for jewelry use, faceted pieces would be great additions to collections of rare gemstones.

Brucite Information

Data Value
Name Brucite
Colors White, pale green, gray, bluish. Manganoan variety yellow to brownish-red, brown.
Crystallography Hexagonal; tabular crystals, platy aggregates. Manganoan variety sometimes acicular. Also foliated, massive, fibrous, scaly.
Refractive Index 1.559-1.600
Luster Waxy to vitreous; pearly on cleavages.
Hardness 2.5
Wearability Display Only
Fracture Fibrous
Specific Gravity 2.39
Birefringence 0.010-0.020
Cleavage Perfect basal cleavage
Luminescence May fluoresce blue-white or light green.
Luminescence Present Yes
Luminescence Type Fluorescent
Transparency Transparent to translucent.
Formula

Mg(OH)2

Pleochroism

None; colorless in transmitted light.

Optics

o = 1.559-1.590; e = 1.580-1.600. Uniaxial (+); sometimes biaxial with small 2V.

Optic Sign Uniaxial +, Biaxial +
Etymology

After Archibald Bruce, an early American mineralogist who first described the species.

Occurrence

In low temperature hydrothermal veins in serpentine, chloritic and dolomite schists, and metamorphic limestones.

yellow brucite crystals - Pakistan

This cluster of inter-grown, lemon-yellow brucites “looks like a tree with a canopy over it.” 5.0 x 3.3 x 3.1 cm, Killa Saifullah District, Balochistan, Pakistan. © Rob Lavinsky, www.iRocks.com. Used with permission.

Comments

The mineral brucite has many industrial uses, such as serving as an magnesium ore. However, it rarely occurs in cuttable crystals. It has a hardness of only 2.5, so a coin could scratch its surface. With sectile tenacity, it could also be cut with a knife. (When it occurs in fibrous form, brucite can even be elastic). All these factors, combined with perfect cleavage, make this a very difficult material to facet or wear as jewelry.

brucite - Azerbaijan

Brucite, 170 mm, Kyalbajar region, Azerbaijan. Photo by AyselkaDjabrailova. Licensed under CC By-SA 4.0.

Manganoan Brucite

Most brucites show pale white, blue, gray, or green colors. A manganese-rich variety can occur in yellow, reddish brown, and dark brown.

Nemalite

A fibrous variety of brucite.

Nemalite, brucite variety - Vermont

Brucite variety nemalite in pale green antigorite from the Eden Mills mines in Vermont, USA. Photo by John Krygier. Public Domain.

Brucite Marble

Brucite can also occur in bands in marble known as brucite marble or ophicalcite.

Identifying Characteristics

Brucites exhibit the pyroelectric effect. They generate an electric charge when heated.

Brucites may show an anomalously biaxial optic character.

Some brucites have blue-white or light green fluorescence.

This pearly white brucite on matrix shows fluorescence under ultraviolet light. 4.1 x 2.8 x 1.2 cm, N’Chwaning II Mine, N’Chwaning Mines, Kuruman, Kalahari manganese fields, Northern Cape Province, South Africa. © Rob Lavinsky, www.iRocks.com. Used with permission.

Although slightly softer than brucite with a hardness of 2, gypsum’s color range overlaps with this mineral’s. However, gypsum also has lower refractive indices (RI) and specific gravity (SG). Gem cutters rarely facet either of these soft minerals, but gypsum is more likely to be finished. It sees more use as material for cabochons and carvings.

Synthetics

Brucite has been synthesized for numerous research projects and commercial purposes, especially as an environmentally friendly flame retardant. However, there is no known jewelry use for this material.

Enhancements

None known.

Sources

Pakistan and South Africa produce lovely crystals and sometimes cuttable material.

Asbestos, Quebec, Canada has produce fibrous masses up to several feet in length as well as cuttable pale blue masses.

Lancaster County in Pennsylvania is perhaps the most well-known source in the United States. In particular, Wood’s Chrome Mine has produced large crystals and plates nearly 20 cm across. Brucite from this source has been called “texalite,” after Texas, Little Britain Township, where the mine is located.

This specimen contains large transparent brucites, front and back views. 19.5 x 14.5 x 3.2 cm, Wood’s Chrome Mine, Texas, Lancaster County, Pennsylvania, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.

Other notable sources include the following:

  • United States: California; Hoboken, New Jersey (type locality, fibrous aggregates); Brewster, New York (small crystals).
  • Italy; Russia; Scotland; Sweden (manganoan variety).

Stone Sizes

Most of the few known faceted brucites range from ½ to 1 carat in size. Asbestos, Quebec, the major source of cuttable material, has yielded pale blue gems up to 1+ carats.

A nearly colorless faceted Russian specimen of 20.18 cts has been reported.

Care

Handle these fragile gems carefully. Clean them only with a soft brush, mild detergent, and warm water. For more care recommendations, consult our gemstone jewelry cleaning guide.

brucite crystal - South Africa

The curves, luster, and color of this brucite crystal give it an almost ocean wave appearance. 7.5 x 6.2 x 4.0 cm, Wessel’s Mine, Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa. © Rob Lavinsky, www.iRocks.com. Used with permission.

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