Rock Identifier
Druzy Agate (Star-cut Geode Slice) (Silicon Dioxide (SiO2) - Microcrystalline and Macrocrystalline Quartz) — mineral
mineral

Druzy Agate (Star-cut Geode Slice)

Silicon Dioxide (SiO2) - Microcrystalline and Macrocrystalline Quartz

Hardness: 6.5-7 Mohs; Color: Pale lavender, grey, and white with black inclusions; Luster: Vitreous to waxy; Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Gravity: 2.60-2.65.

Hardness
6
Color
Pale lavender, grey, and white with black inclusions
Luster
Vitreous to waxy
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Physical properties

Hardness: 6.5-7 Mohs; Color: Pale lavender, grey, and white with black inclusions; Luster: Vitreous to waxy; Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Gravity: 2.60-2.65.

Formation & geological history

Formed as secondary deposits in volcanic rock cavities (vesicles). Silica-rich groundwater percolates through voids, depositing layers of chalcedony (agate) and then crystalline druzy quartz. Often associated with Cretaceous or Tertiary volcanic fields.

Uses & applications

Primarily used for ornamental purposes, lapidary carvings (like this star shape), jewelry, and metaphysical collecting.

Geological facts

The 'druzy' refers to the tiny, glittering crystals covering the surface of the center; this specific specimen features black inclusions which are often Goethite or Manganese oxides.

Field identification & locations

Identify by the distinctive concentric banding of agate surrounding a crystalline 'sugar' center. Commonly sourced from Brazil or Uruguay. Collectors look for clarity in banding and lack of fracture lines.

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