Mineral on Sedimentary Rock

Druzy Quartz on Matrix (likely Limestone or Sandstone)

Silicon Dioxide (SiO2) with various trace impurities

Hardness: 7 (Quartz) vs 3-4 (Matrix); Color: Pale brown, tan, and translucent white; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) micro-crystals; Cleavage: None/Conchoidal

Hardness: 7 (Quartz) vs 3-4 (Matrix)
Color: Pale brown, tan, and translucent white
Luster: Vitreous to waxy

Identified March 19, 2026More mineral on sedimentary rock →

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Physical properties

Hardness: 7 (Quartz) vs 3-4 (Matrix); Color: Pale brown, tan, and translucent white; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) micro-crystals; Cleavage: None/Conchoidal

Formation & geological history

Formed by the precipitation of silica-rich hydrothermal fluids or groundwater within cavities/vugs of sedimentary rock. Typical geological age varies from 10 to 450 million years depending on the host formation.

Uses & applications

Used primarily for geological collecting, home decor, and metaphysical display. Larger high-quality clusters may be used for lapidary work or semi-precious carvings.

Geological facts

The term 'druzy' refers to the tiny glittering crystals that coat the surface of the host rock. This specimen appears to be a 'vug', a hollow space in the rock that allowed the crystals to grow without being crushed.

Field identification & locations

Identify by checking hardness (Quartz will scratch glass) and looking for tiny sparkling crystal faces in the sunlight. Common in regions with karst topography or old hydrothermal activity like the Midwestern USA or Brazil.

Other mineral on sedimentary rock specimens

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Limonite Concretion

Limonite (Hydrated Iron Oxide) FeO(OH)·nH2O

sedimentary

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

sedimentary

Limonite Concretion (Ironstone)

Limonite (FeO(OH)·nH2O) / Goethite

sedimentary

Chalcedony in Limestone Host Rock

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Mineral within Sedimentary Rock

Quartz (chalcedony variety) or Limestone with Quartz Veins

SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)

Mineral or Sedimentary Rock (with mineral inclusions)

Manganese Oxide Crust on Limestone

Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3

sedimentary