igneous
Quartz with Feldspar
Silicon Dioxide (SiO2) with Potassium Feldspar (KAlSi3O8)
Hardness of 6-7 on Mohs scale; colors range from milky white and translucent gray to tan/yellowish iron staining; vitreous to pearly luster; lacks obvious cleavage in quartz parts but shows blocky cleavage in feldspar; irregular to conchoidal fracture.
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Physical properties
Hardness of 6-7 on Mohs scale; colors range from milky white and translucent gray to tan/yellowish iron staining; vitreous to pearly luster; lacks obvious cleavage in quartz parts but shows blocky cleavage in feldspar; irregular to conchoidal fracture.
Formation & geological history
Formed from the slow cooling of silica-rich magma within the Earth's crust, likely as part of a granite pegmatite or a hydrothermal vein system. Common in Precambrian or younger igneous terrains.
Uses & applications
Primary source of silica for glass making and electronics; feldspar is used in ceramics and abrasives. Raw specimens are common in landscaping or as beginner collector pieces.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. This specimen shows a typical intrusive igneous texture where minerals intergrow as they crystallize from molten rock.
Field identification & locations
Identify in the field by its hardness (scratches glass), white-to-tan color, and lack of reaction to acid. Commonly found in mountainous regions or glacial till. Look for the distinct glassy luster of quartz mixed with the blocky, opaque look of feldspar.
