sedimentary

Quartz Conglomerate

Quartz Conglomerate (clastic sedimentary rock)

Hardness: 7 (Mohs scale for quartz clasts); Color: Milky white, grey, or tan; Luster: Vitreous to dull; Structure: Large, rounded clasts (>2mm) in a finer-grained matrix; Cleavage: None in the rock itself; specific gravity approx 2.6-2.7.

Hardness: 7 (Mohs scale for quartz clasts)
Color: Milky white, grey, or tan
Luster: Vitreous to dull

Identified February 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in high-energy aqueous environments like river beds or beaches where water movement is strong enough to transport and round large stones. Over millions of years, these sediments are buried and lithified by pressure and mineral cementation.

Uses & applications

Used as aggregate in construction, road base material, and decorative landscaping stones. Higher quality slabs are sometimes used in architectural facing.

Geological facts

Often called the 'mother of gold' by early prospectors because gold can sometimes be trapped in the matrix of ancient conglomerate beds. It is essentially a fossilized riverbed.

Field identification & locations

Identify in the field by looking for 'pudding stone' textures with rounded pebbles embedded in a concrete-like matrix. Commonly found in ancient sedimentary basins and along uplifted coastlines. Collectors look for unique color contrast between clasts and matrix.

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