sedimentary
Conglomerate
Sedimentary Conglomerate with Basaltic Clast
Hardness: 3-7 (variable based on matrix and clasts); Color: Grey, tan, brown; Luster: Dull or earthy; Structure: Clastic; Cleavage: None; SG: 2.5-2.8
- Hardness
- 3-7 (variable based on matrix and clasts)
- Color
- Grey, tan, brown
- Luster
- Dull or earthy
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Physical properties
Hardness: 3-7 (variable based on matrix and clasts); Color: Grey, tan, brown; Luster: Dull or earthy; Structure: Clastic; Cleavage: None; SG: 2.5-2.8
Formation & geological history
Formed when large rounded fragments (clasts) are cemented together by finer-grained matrix like sand or silt. This specimen shows a large basaltic cobble partially encased in a lithified sandy matrix, likely formed in a high-energy river or beach environment.
Uses & applications
Primarily used as coarse aggregate in construction, road base, or as an ornamental stone in landscaping. Some unique specimens serve as decorative curiosities for collectors.
Geological facts
Conglomerates are often called puddingstones because of their resemblance to Christmas pudding. They provide geologists with a record of ancient water flow direction and energy levels.
Field identification & locations
Identify by looking for rounded rock fragments of various sizes bonded together by a natural mineral cement. Large rounded stones sticking out of a finer 'concrete-like' body are characteristic. Found in riverbeds and coastal areas.
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