igneous
Quartz–feldspar pegmatite with pink tourmaline
Granitic pegmatite; predominantly quartz (SiO₂), microcline/orthoclase (KAlSi₃O₈), albite (NaAlSi₃O₈), and likely elbaite tourmaline (Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
AI-generated identification · may be incorrectCoarse, interlocking crystals with white to gray quartz/feldspar and abundant pink-red prismatic or granular tourmaline; vitreous quartz luster and pearly feldspar luster. Quartz hardness 7, feldspar 6–6.5, tourmaline 7–7.5; feldspar shows cleavage, quartz lacks cleavage.
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Physical properties
Coarse, interlocking crystals with white to gray quartz/feldspar and abundant pink-red prismatic or granular tourmaline; vitreous quartz luster and pearly feldspar luster. Quartz hardness 7, feldspar 6–6.5, tourmaline 7–7.5; feldspar shows cleavage, quartz lacks cleavage.
Formation & geological history
Formed from volatile-rich granitic magma during the late stages of crystallization, producing exceptionally large crystals and lithium-bearing minerals; commonly Precambrian to Mesozoic, depending on the pegmatite province.
Uses & applications
Collected as a mineral specimen; gem-quality tourmaline may be cut for jewelry, while feldspar and quartz have industrial uses. Pegmatite is rarely used structurally when specimen-grade.
Geological facts
The pink material may be elbaite or rubellite tourmaline, though garnet or altered feldspar is also possible from the image alone.
Field identification & locations
Look for glassy quartz, blocky feldspar cleavage, and tourmaline’s striated prismatic crystals; common in Brazil, Afghanistan, Pakistan, Madagascar, California, and Maine. A loupe, hardness tests, and chemical or Raman analysis can confirm species.
