mineral

Ferruginous Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Hematite)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: White to milky with reddish-brown staining; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.

Hardness: 7 (Mohs scale)
Color: White to milky with reddish-brown staining
Luster: Vitreous to dull

Identified June 29, 2026More mineral →

Explore Ferruginous Quartz in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7 (Mohs scale); Color: White to milky with reddish-brown staining; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.

Formation & geological history

Formed through hydrothermal processes where silica-rich fluids crystallize in veins or cavities. The reddish-brown staining is caused by secondary iron oxide minerals (limonite or hematite) leaching into cracks and surfaces. Common in the Schwaner Mountains and varied geological settings of Kalimantan.

Uses & applications

Used primarily for industrial glass making, filtration, and as a decorative mineral specimen. In jewelry, clear varieties are faceted, but this rough specimen is mostly for geological study or collection.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Specimens found in tropical regions like Borneo often exhibit heavy staining due to intense chemical weathering (lateritization) of surrounding soils.

Field identification & locations

Identify in the field by its ability to scratch glass and its lack of cleavage. In Central Kalimantan (0.9°S, 113.9°E), it is often found in riverbeds or near igneous outcrops associated with the Mueller or Schwaner ranges.