Tumbled dumortierites are polished specimens of a borosilicate mineral primarily composed of aluminum and boron, with the chemical formula Al₇BO₃(SiO₄)₃O₃. Known for their deep blue to violet colors, these stones display the mineral’s fibrous texture and strong pleochroism when viewed from different angles.
Features:
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Composition: Dumortierite is an aluminum borosilicate mineral that forms in metamorphic rocks, often associated with quartz and feldspar.
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Appearance: Typically vibrant blue to violet, sometimes with streaks or patches of lighter shades. The tumbled finish enhances the stone’s natural color and silky luster.
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Formation: Commonly forms in high-temperature regional metamorphic environments, especially in aluminum-rich sediments subjected to intense pressure and heat.
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Physical Properties: Hard and durable (Mohs hardness of 7–8), with a fibrous to granular crystal habit.
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Educational Value: Useful for illustrating metamorphic mineral formation, crystal structure, and optical properties like pleochroism.
Tumbled dumortierites are attractive specimens for geology enthusiasts, collectors, and educators seeking examples of mineralogical diversity and metamorphic processes.
