Correct Answer - Option 1 : lodes
- Minerals are solid chemical compounds with a fairly well-defined chemical composition and a specific crystal structure, that occurs naturally in pure form.
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Example- calcium, chloride, magnesium, phosphorus, potassium, sodium, etc.
- In igneous and metamorphic rocks, minerals occur in Veins and Lodes.
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Veins- Smaller occurrences of minerals in cracks, faults, joints, and crevices of the igneous and metamorphic rocks are Veins.
- Lodes- Larger occurrences of minerals in cracks, faults, joints, and crevices of the igneous and metamorphic rocks are Lodes.
- Minerals found in Veins and Lodes are- Lead, Copper, Tin, and Zinc.
Hence, minerals occur in lodes in igneous and metamorphic rocks.
Minerals generally occur in these forms:
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In igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults, or joints. The smaller occurrences are called veins and the larger ones are called lodes. Example- Lead, Copper, Tin.
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In sedimentary rocks, a number of minerals occur in beds or layers. They have been formed as a result of deposition, accumulation, and concentration in horizontal strata. Example- Coal, Gypsum, Sodium salt.
- The decomposition of surface rocks, and the removal of soluble constituents, leaving a residual mass of weathered material containing ores. Example- Bauxite.
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Placer deposits- Accumulation of valuable minerals formed by gravity separation from a specific source rock during sedimentary processes. The Spanish word placer means" alluvial sand". Example- Gold, Silver, Tin, Platinum.
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Oceanic beds- The ocean waters contain vast quantities of minerals, but most of these are too widely diffused to be of economic significance. Example- common salt, magnesium, manganese nodules, and bromine
