igneous
Quartz in Host Rock
Silicon Dioxide (SiO2) in Rhyolite or Granite matrix
Hardness: 7 (Quartz) / 6-6.5 (Matrix); Color: Milky white to clear quartz in a grayish-pink/tan rocky matrix; Luster: Vitreous (glassy) for quartz, earthy for matrix; Structure: Crystalline quartz vein within a fine-grained igneous rock.
- Hardness
- 7 (Quartz) / 6-6
- Luster
- Vitreous (glassy) for quartz, earthy for matrix
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Physical properties
Hardness: 7 (Quartz) / 6-6.5 (Matrix); Color: Milky white to clear quartz in a grayish-pink/tan rocky matrix; Luster: Vitreous (glassy) for quartz, earthy for matrix; Structure: Crystalline quartz vein within a fine-grained igneous rock.
Formation & geological history
Formed through the cooling of silica-rich magma or from hydrothermal fluids filling cracks (veins) in existing rock. These specimens can range from millions to over a billion years old depending on the regional geological history of the find-site.
Uses & applications
Quartz is used in glassmaking, electronics (oscillators), and as an abrasive. Specimens like this are primarily used for geological education or as low-level lapidary practice. High-grade quartz is used in jewelry.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. This specific specimen shows a 'vein,' which represents the final stage of mineral crystallization in a cooling magma body where water-rich fluids deposit concentrated silica.
Field identification & locations
Identify in the field by checking the hardness (quartz will scratch glass) and looking for the distinct glassy luster of the white inclusion compared to the surrounding dull rock. Found globally in mountainous or volcanically active regions.
