metamorphic

Iron-stained quartz pebble (likely quartzite)

Quartz-rich rock, probably quartzite; predominantly silicon dioxide (SiO₂) with iron-oxide staining

AI-generated identification · may be incorrect

Opaque, rounded pebble with cream-gray and rusty-brown mottling and a rough, granular surface. Quartz has Mohs hardness 7, vitreous to dull luster, and no cleavage; the image does not show enough detail to confirm quartzite versus iron-stained vein quartz.

Identified September 27, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartz-rich material formed from silica-rich sediment or a hydrothermal vein; if quartzite, burial and metamorphism fused quartz grains. Iron oxides produced the rusty coloration. Exact age cannot be determined from the photo.

Uses & applications

Commonly collected as a pebble or used as aggregate and landscaping stone; this small, ordinary piece is unlikely to have significant commercial value.

Geological facts

Rusty colors commonly come from hematite or goethite coating or staining quartz, rather than from the quartz itself.

Field identification & locations

The rounded shape suggests transport by water or weathering. A scratch test against glass (quartz should scratch it) and a fresh broken surface can help distinguish quartz-rich rock from softer lookalikes; the reported Mexican location is plausible but not diagnostic.