mineral

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Hematite/Limonite) inclusions

Hardness: 7 on Mohs scale; Color: Reddish-orange, peach, or rusty brown; Luster: Vitreous to greasy; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Reddish-orange, peach, or rusty brown
Luster: Vitreous to greasy

Identified March 19, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Reddish-orange, peach, or rusty brown; Luster: Vitreous to greasy; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed through hydrothermal processes or secondary staining of quartz crystals by iron-rich groundwater. Often found in sedimentary deposits or as weathered vein quartz, dating from any geological period where silica and iron were present.

Uses & applications

Primary use is in aesthetic jewelry (beads, cabochons), lapidary art, and rock collecting. Historically used for carving and as a decorative stone.

Geological facts

Also known as 'Eisenkiesel' in German (meaning iron-pebble). The red color is caused by microscopic hematite or goethite crystals trapped inside the quartz matrix or coating the exterior surfaces.

Field identification & locations

Identify in the field by its superior hardness (cannot be scratched by a steel knife) and the characteristic sparkle of quartz underlying the rusty hue. Found globally in iron-rich soils, riverbeds, and quartz veins.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral