mineral

Quartz Geode (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Yellow to amber with white crystalline centers; Luster: Vitreous to greasy; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture).

Hardness: 7 on Mohs scale
Color: Yellow to amber with white crystalline centers
Luster: Vitreous to greasy

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Yellow to amber with white crystalline centers; Luster: Vitreous to greasy; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed by hydrothermal fluids or groundwater rich in silica depositing crystals inside rock cavities (vugs). The yellow color is due to iron impurities or natural irradiation over millions of years.

Uses & applications

Used primarily for ornamental displays, lapidary work, jewelry (when cut into gemstones), and by mineral collectors for its aesthetic crystalline structure.

Geological facts

Small quartz-filled nodules like this are often called 'potato stones' or geodes. While most quartz is clear or milky, iron staining commonly turns them the yellow color seen here, mimicking natural citrine.

Field identification & locations

Identify in the field by looking for rounded, lumpy nodules that feel lighter than solid rocks. Use a rock hammer to reveal the crystalline interior. Common in sedimentary regions and volcanic ash beds.

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