mineral

Quartz geode / druzy quartz in iron-stained host rock

Quartz, SiO₂; likely chalcedony and iron oxides in the outer matrix

AI-generated identification · may be incorrect

White to translucent gray, sparkling microcrystals with orange-brown iron staining; vitreous luster and probable hexagonal quartz crystals. Hardness 7 Mohs, no cleavage, conchoidal fracture, specific gravity about 2.65.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater filled a cavity in volcanic or sedimentary rock, depositing chalcedony and later quartz crystals. The specimen’s exact age cannot be determined visually; Brazilian and Paraguayan geodes commonly formed in Mesozoic volcanic settings.

Uses & applications

Used as a decorative, lapidary, and collecting specimen; polished or cut geodes are popular ornaments. This small irregular piece has limited commercial use.

Geological facts

The rusty orange coloration is typically caused by hematite/goethite inclusions rather than the quartz itself. The reported location in northern Paraguay is regionally plausible for quartz-bearing geodes and silica-rich materials.

Field identification & locations

Identify by the hard, glassy, sparkly quartz surface and inability to scratch it with a steel knife; quartz should scratch glass. A vinegar test is not diagnostic, while a hardness, streak, and crystal examination are more useful.