These specimens feature black tourmaline (schorl) embedded within clear or milky quartz (SiO₂), combining two common rock-forming minerals in a single polished stone. The striking contrast of dark, needle-like tourmaline inclusions within a lighter quartz matrix makes it a visually distinct and geologically informative sample.
Features:
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Composition: The quartz is composed of silicon dioxide, while the tourmaline is a complex borosilicate mineral rich in iron, giving it a black appearance. Both minerals are durable and commonly found together in metamorphic and igneous environments.
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Appearance: Tourmaline appears as black rods or streaks—often radiating or intersecting—within translucent or opaque quartz. The tumbled finish highlights this natural contrast and enhances surface smoothness.
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Formation: Forms in high-temperature environments such as granite pegmatites or regional metamorphic rocks, where tourmaline crystals grow within silica-rich fluids that later solidify into quartz.
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Educational Value: Excellent for illustrating mineral inclusion, crystallization processes, and the coexistence of multiple minerals in a single geologic setting.
These polished pieces are well suited for teaching, collecting, or display, showing how complex mineral growth can occur in natural rock-forming environments.
