Sedimentary rocks:
Rocks formed by sedimentation or accumulation and consolidation of sediments.
Weathering:
Classification of sedimentary rock:
| Grades | Grain size | Rock type |
| Gravel or pebble | 2mm and over | Conglomerates |
| Sand | 0.1mm to 2mm | Sandstone |
| Silt | 0.01mm to 0.1mm | Siltstone |
Minerals of sedimentary rocks:
Most sedimentary rocks contain either quartz (especially siliciclastic rocks) or calcite (especially carbonate rocks). Carbonate rocks dominantly consist of carbonate minerals like calcite, aragonite or dolomite. Both cement and clasts (including fossils and ooids) of a carbonate rock can consist of carbonate minerals The stability of the major rock forming minerals (their resistance to weathering). In this series, quartz is most stable, followed by feldspar, micas, and other less stable minerals that are only present when little weathering has occurred.[25] The amount of weathering depends mainly on the distance to the source area, the local climate and the time it took for the sediment to be transported there. In most sedimentary rocks, mica, feldspar and less stable minerals have reacted to clay minerals like kaolinite, illite or smectite.
Moh’s scale of hardness:
(based on resistance to scratch)
1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Orthoclase
7. Quartz
8. Topaz
9. Corundum
10. Diamond
Conglomerates:
The pebbles and gravels on consolidation and cementation produce a rock known as conglomerates.the pores of conglomerate are filled with sand,rock particle and some cementing material.
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