Describe in brief the five forms of mineral occurrence.
Mineral generally occurs in following forms:
- Igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults or joints, such smaller occurrences are called viens and largers are called loads. Major metallic minerals like tin, copper, zinc and lead etc., are obtained from viens and loads.
- In sedimentary rocks, a number of minerals occur in beds or layers. They have been the result of depositions, accumulation and concentration in horizontal strata. Coal, gypsum, potash, salt and sodium comes under this category of mineral function.
- Another mode of formation involves the deposition of surface rocks and the removal of soluble constituents leaving a residual mass of weathered material containing ores. Bauxite is formed this way.
- Certain minerals may occur as alluvial deposits in sands of valley floors and the base of hills, gold, silver, tin and platinum occur in such a way.
- The ocean waters contain vast quantity of minerals common salt, magnesium and bromine are largely derived from ocean waters.