sedimentary
Conglomerate
Quartz Conglomerate
Hardness 6-7 (quartz pebbles), variable matrix hardness. Colors consist of off-white to yellowish quartz pebbles in a tan-brown sandy/iron-stained matrix. Dull to vitreous luster on pebbles, clastic texture with rounded clasts.
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Physical properties
Hardness 6-7 (quartz pebbles), variable matrix hardness. Colors consist of off-white to yellowish quartz pebbles in a tan-brown sandy/iron-stained matrix. Dull to vitreous luster on pebbles, clastic texture with rounded clasts.
Formation & geological history
Formed in high-energy environments like riverbeds, alluvial fans, or beaches where pebbles are rounded by water action and then cemented together by minerals like silica, calcite, or iron oxide.
Uses & applications
Used primarily as crushed stone in construction, decorative landscaping rock, and occasionally polished into cabochons or polished pebbles for collectors.
Geological facts
Often referred to as 'puddingstone' when rounded, distinct brightly colored pebbles are cemented in a contrasting fine matrix. Large quartz conglomerates are common worldwide.
Field identification & locations
Identified by rounded pebbles (clasts) larger than 2mm embedded in a finer matrix. Commonly found along river banks, ancient lakebeds, and beach deposits.
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