Rock Identifier
Banded quartz-rich pebble, possibly jasper or agate (Microcrystalline quartz (SiO₂), likely chalcedony/jasper with iron-oxide staining) — mineral
mineral

Banded quartz-rich pebble, possibly jasper or agate

Microcrystalline quartz (SiO₂), likely chalcedony/jasper with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; cream, tan, brown, and gray banding with a dull to slightly waxy luster. Microcrystalline quartz lacks visible crystal faces and has no cleavage; specific gravity is roughly 2.6.

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Physical properties

Hardness about 6.5–7 Mohs; cream, tan, brown, and gray banding with a dull to slightly waxy luster. Microcrystalline quartz lacks visible crystal faces and has no cleavage; specific gravity is roughly 2.6.

Formation & geological history

Formed when silica-rich groundwater filled cavities or fractures, later developing chalcedony and opaque jasper bands; iron oxides produced the brown coloration. The specimen’s precise geological age and locality cannot be determined from the image.

Uses & applications

Used as a decorative stone, lapidary material, cabochons, beads, and tumbled stones; ordinary pebbles have little industrial value.

Geological facts

The rounded shape indicates transport and abrasion in a stream, beach, or gravel deposit. Agate is typically translucent with sharper rhythmic banding, whereas jasper is more opaque and iron-rich.

Field identification & locations

Look for quartz-like hardness, inability to scratch it with a steel knife, waxy texture, and curved or irregular bands; acid does not fizz. Common sources include Brazil, Uruguay, India, Madagascar, and many regional gravel deposits.