metamorphic
Yellow Aventurine
Quartzite with inclusions (SiO2)
Hardness: 7 (Mohs scale); Color: Pale yellow to golden-orange; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.64-2.69.
- Hardness
- 7 (Mohs scale)
- Color
- Pale yellow to golden-orange
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale yellow to golden-orange; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.64-2.69.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. The yellow hue is caused by inclusions of mica (muscovite) or iron-bearing minerals (like pyrite or goethite) within the quartz matrix. Most deposits are Proterozoic to Paleozoic in age.
Uses & applications
Primarily used for lapidary work, jewelry (beads and cabochons), ornamental carvings, and 'healing' stones. In industry, high-purity quartzites can be used for building stone or road aggregate, though aventurine is specifically sought for its aesthetic qualities.
Geological facts
Yellow Aventurine is often called a 'stone of self-reflection.' It is closely related to green aventurine, but the color change is due to specific mineral inclusions like hematite or mica rather than fuchsite. This specimen has been 'tumbled'—polished in a machine with grit to smooth its naturally jagged edges.
Field identification & locations
Identify in the field by its hardness (will scratch glass), greasy luster when polished, and subtle 'aventurescence' (a shimmering effect from internal mineral plates). Common locations include India, Brazil, and Russia. Collectors should look for uniform color and lack of deep cracks.
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