igneous and sedimentary

Jasper and Basalt Pebble

Polymineralic lithic pebble

Hardness ranges from 6 to 7 on the Mohs scale depending on the specific mineral zone. Color is mottled grey, green, and brown. Luster is dull to sub-vitreous. Microcrystalline and crypto-crystalline structure with no prominent cleavage. Specific gravity is approximately 2.6 to 2.9.

Identified August 7, 2026More igneous and sedimentary →

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Physical properties

Formation & geological history

Formed through a combination of volcanic activity creating the basaltic component and silica-rich deposition forming the jasper inclusions, subsequently weathered, eroded, and smoothed into a pebble by water transport in a river or marine environment.

Uses & applications

Used primarily as decorative gravel, landscaping, tumbling material, or as a specimen for amateur rockhound collections.

Geological facts

Pebbles like this show the complex geological history of an area, often bringing together different rock types from distant upstream sources through fluvial transport.

Field identification & locations

Commonly found in riverbeds, lake shores, and beaches. Identified by its water-worn rounded shape and variegated multicolored surface. Look for distinct color patches indicating different mineral assemblages.

Other igneous and sedimentary specimens

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Granite / Arkosic Sandstone (Coarse Igneous or Sedimentary Aggregate)

Granite / Quartz-Feldspar Aggregate

igneous

Quartz (Druzy)

Silicon Dioxide (SiO2)

mineral

Basalt with Chert or Jasper Inclusion

Igneous basalt / sedimentary chert nodule

igneous

Botryoidal Chalcedony

Chalcedony (SiO2)

Mineral

Greenstone (Greywacke or Nephrite Jade variant)

Metamorphosed mafic igneous or sedimentary rock (e.g., Actinolite-Chlorite Schist)

metamorphic

Tumbled Agate

Silicon Dioxide (Chalcedony / Quartz)

gemstone