igneous
Quartz–feldspar pegmatite with iron-oxide staining
Granitic pegmatite; predominantly SiO₂ quartz with K-feldspar/plagioclase and likely Fe-oxide minerals
AI-generated identification · may be incorrectVery coarse-grained, with translucent to white quartz and pink-to-red feldspar; vitreous quartz luster, blocky feldspar cleavage, and possible sparkling mica. Quartz hardness is 7 Mohs; feldspar is about 6–6.5, with medium-high specific gravity around 2.6–2.7.
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Physical properties
Very coarse-grained, with translucent to white quartz and pink-to-red feldspar; vitreous quartz luster, blocky feldspar cleavage, and possible sparkling mica. Quartz hardness is 7 Mohs; feldspar is about 6–6.5, with medium-high specific gravity around 2.6–2.7.
Formation & geological history
Formed when volatile-rich residual magma cooled slowly in a granitic intrusion, allowing exceptionally large crystals to grow. Most pegmatites are Precambrian to Phanerozoic, though this specimen’s age and locality cannot be determined visually.
Uses & applications
Collected as a mineral specimen and sometimes used as ornamental stone; pegmatites are important sources of feldspar, quartz, mica, lithium, tantalum, and rare gemstones.
Geological facts
The red coloration is likely hematite or iron-stained feldspar, while the pale sparkling patches may be quartz or mica. Pegmatites can host tourmaline, beryl, garnet, and lithium minerals.
Field identification & locations
Identify by its unusually coarse crystals, glassy quartz, pink feldspar, and lack of layering or foliation; common in granitic terrains worldwide, including Maine, California, Brazil, and Madagascar. A locality label or tests for hardness and cleavage would improve identification.
