mineral
Likely black tourmaline (schorl)
Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
AI-generated identification · may be incorrectThe dark, elongated appearance is consistent with tourmaline, but the image is too blurred for confident identification. Schorl has Mohs hardness 7–7.5, a vitreous luster, commonly striated prismatic crystals, and poor cleavage.
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Physical properties
The dark, elongated appearance is consistent with tourmaline, but the image is too blurred for confident identification. Schorl has Mohs hardness 7–7.5, a vitreous luster, commonly striated prismatic crystals, and poor cleavage.
Formation & geological history
Schorl crystallizes in boron-rich granitic pegmatites and hydrothermal veins, often alongside quartz and feldspar; its age depends on the host deposit.
Uses & applications
Used as a mineral specimen and occasionally in jewelry; tourmaline varieties are also collected as gemstones.
Geological facts
Tourmaline crystals commonly show strong lengthwise striations and can be electrically charged by heating or friction.
Field identification & locations
Look for a hard, black, elongated prism with parallel grooves; common sources include pegmatites in Brazil, Africa, and the United States. A clearer image or hardness and streak tests would help distinguish it from other dark minerals.
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Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
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igneous
Unidentified pink-and-gray mineral or rock specimen
Undetermined; the image is too blurry for reliable identification
mineral