Petroleum Geology Overview
Sedimentary rock types

Terrigenous sediments (clastic)  

These are land derived sediments sub-divided further on the basis of their grain size.

- Group A - Clays (particles with a diameter less than 0.004 mm)
- Group B - Silts (particle diameter 0.004 to 0.06 mm)
- Group C - Sands (particle diameter 0.06 mm to 2 mm)
- Group D - Rudites (coarser rock fragments).  

Clay

1- Clay minerals are hydrous platy aluminosilicates. 

2-
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