Conglomerate

Physical Properties

Hardness: 6-7 (dictated by quartz clasts); Color: Gray-green matrix with tan and white clasts; Luster: Dull to waxy; Structure: Clastic with rounded pebbles set in a fine-grained matrix; Specific Gravity: 2.6-2.8.

Formation & Geological History

Formed through the lithification of rounded river or beach gravel transport by high-energy water environments. These specimens often date from various geological eras where coastal or fluvial deposition occurred.

Uses & Applications

Primarily used as a decorative stone in landscaping, a coarse aggregate in the construction industry, or as a lapidary material for 'puddingstone' jewelry.

Geological Facts

Commonly known as 'Puddingstone' when the clasts contrast sharply with the matrix. It serves as a geological indicator of past high-energy water flow, such as ancient riverbeds or wave-beaten shorelines.

Field Identification & Locations

Identify by looking for rounded, water-worn pebbles cemented within a finer matrix. Often found on beaches, riverbanks, and in glacial till throughout the Great Lakes region and coastal areas.

Identified on: 5/3/2026

Mode: Standard