Brookite Value, Price, and Jewelry Information
Brookite usually occurs in very dark colors, transparent only in small fragments. Cuttable crystals are exceedingly rare, making attractive faceted gems prized collector’s items.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Orthorhombic. Occurs only in crystals; tabular, prismatic, pyramidal; often striated.|
|Colors||Brown, yellow brown, reddish brown, dark brown to black; rarely blue.|
|Luster||Adamantine to submetallic.|
|Specific Gravity||4.14 normal; 3.87-4.14.|
|Transparency||Transparent to opaque.|
|Pleochroism||Strong: yellow-brown/ reddish-brown/ orange to golden brown. An hourglass-shaped zonal coloration is sometimes seen in bluish crystals.|
|Optics||a = 2.583; β = 2.584; γ = 2.700–2.740. Biaxial (+)|
|Etymology||After the English mineralogists and crystallographer J.H. Brooke. Arkansite is named after the US state of Arkansas.|
|Occurrence||In gneisses, schists, and sometimes in igneous rocks; contact deposits.|
Although not a very rare mineral, brookite crystals typically form in thin tabular shapes. This makes cutting gemstones very difficult. Although brookites have dispersion that exceeds that of diamonds, their dark colors and possibly submetallic luster can mask their fire. Due to these factors, you’re more likely to find faceted brookites in gem collections than jewelry collections.
A black, opaque, and bipyramidal brookite variety, arkansite occurs in the eastern Siberian region of Russia and Magnet Cove, Arkansas, USA.
Some quartz specimens from Brazil contain striking, “insectile” inclusions of brookite blades and rutile needles. These have been marketed as “platinum quartz.” The name most likely alludes to the metallic appearance of the inclusions, although they contain no platinum. (Please note that so-called “platinum aura quartz” refers to possibly diffusion-treated quartz, not the included material).
Brookite has over the limit (OTL) refractive indices of 2.583-2.740.
This gem shares some properties with another rarely faceted mineral, rutile. These fellow polymorphs have overlapping ranges of color and refractive index (RI). Nevertheless, rutiles usually have uniaxial optic character while brookites have biaxial. Rutiles also have heavier specific gravity (SG) than brookites.
Scientists have synthesized brookite crystals hydrothermally for various projects and commercial applications, including research into its photocatalytic properties (like its fellow polymorph, anatase). However, there’s no known jewelry use for this lab-created material.
Pakistan produces beautiful crystals as well as cuttable material.
Other notable sources include the following:
- United States: Magnet Cove, Arkansas (contact metamorphic rocks); California; Maine; Somerville, Massachusetts; Ellenville, New York (hydrothermal deposits); North Carolina.
- United Kingdom: Dartmoor, England; Wales.
- Minas Gerais, Brazil; France; Russia; Tirol, Switzerland (typical Alpine deposits).
Transparent stones always weigh less than 1-2 carats. Larger stones are opaque.
Of the gem-quality titanium dioxide polymorphs, brookites have the best wearability since they have indistinct cleavage. However, they still have a hardness of 5.5 to 6, which makes them somewhat susceptible to scratching. Use protective settings for jewelry wear and store these gems separately from harder stones to avoid contact scratches. Avoid mechanical cleaning systems. Clean brookites with a soft brush, mild detergent, and warm water. For more care recommendations, consult our gemstone jewelry cleaning guide.