Question

What are the primary and secondary minerals of shale

Answer 1

Answer:

Primary minerals include both the essential minerals used to assign a classification name to the rock and the accessory minerals present in lesser abundance. In contrast to primary minerals are secondary minerals, which form at a later time through processes such as weathering and hydrothermal alteration

Answer 2

Answer:

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Primary mineral, in an igneous rock, any mineral that formed during the original solidification (crystallization) of the rock. Primary minerals include both the essential minerals used to assign a classification name to the rock and the accessory minerals present in lesser abundance. In contrast to primary minerals are secondary minerals, which form at a later time through processes such as weathering and hydrothermal alteration. Primary minerals form in a sequence or in sequential groups as dictated by the chemistry and physical conditions under which the magma solidifies. Accessory minerals form at various times during the crystallization, but their inclusion within essential minerals indicates that they often form at an early time.

Devitrification, process by which glassy substances change their structure into that of crystalline solids. Most glasses are silicates (compounds of silicon, oxygen, and metals) in which the atomic structure does not have the repetitive arrangement required for the formation of crystals. Glass is formed by the cooling of a rock magma too rapidly for this structural regularity to become established. Glasses typically are not stable at low temperatures, however, and a readjustment of the atomic arrangement may take place to form more stable structures. This devitrification process is very slow, but over millions of years, a glass will form a completely crystalline mass; thus, the occurrence of very old glassy rocks is rare.