There are three main classes of Rocks. They are classified according to how they originated. Igneous rocks form from cooling bodies of magma. Over time, various weathering processes erode these rocks and the resulting particles or chemicals settle into beds and are compressed and cemented into sedimentary rocks.
For analysis of hydrocarbon potential, rocks are defined as aggregates or mixtures of minerals plus pores. Any analysis of the extent to which hydrocarbons are trapped in the formation and whether those hydrocarbons can be removed from the rock pores and produced has to begin with an analysis of the rocks themselves.
Sedimentary rock - Classification of sandstones: There are many different systems of classifying sandstones, but the most commonly used schemes incorporate both texture (the presence and amount of either interstitial matrix—i.e., clasts with diameters finer than 0.03 millimetre—or chemical cement) and mineralogy (the relative amount of ...
What Are Sedimentary Rocks? Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks. Clastic sedimentary rocks such as breccia, conglomerate, sandstone, siltstone, and shale are formed from mechanical weathering debris.