Source
The source of heavy mineral sands is in a hardrock source within the erosional areas of a river which carries its load of sediment into the ocean, where the sediments are caught up in littoral drift or longshore drift. Rocks are occasionally eroded directly by wave action shed detritus, which is caught up in longshore drift and washed up onto beaches where the lighter minerals are winnowed.
The source rocks which provide the heavy mineral sands determine the composition of the economic minerals. The source of zircon, monazite, rutile, sometimes tungsten, and some ilmenite is usually granite. The source of ilmenite, garnet, sapphire and diamond is ultramafic and mafic rocks, such as kimberlite or basalt. Garnet is also sourced commonly from metamorphic rocks, such as amphibolite schists. Precious metals are sourced from ore deposits hosted within metamorphic rocks.
Read more about this topic: Heavy Mineral Sands Ore Deposits
Famous quotes containing the word source:
“If, for instance, they have heard something from the postman, they attribute it to “a semi-official statement”; if they have fallen into conversation with a stranger at a bar, they can conscientiously describe him as “a source that has hitherto proved unimpeachable.” It is only when the journalist is reporting a whim of his own, and one to which he attaches minor importance, that he defines it as the opinion of “well-informed circles.””
—Evelyn Waugh (1903–1966)
“The source of all life and knowledge is in man and woman, and the source of all living is in the interchange and the meeting and mingling of these two: man-life and woman-life, man-knowledge and woman-knowledge, man-being and woman-being.”
—D.H. (David Herbert)
“Because relationships are a primary source of self-esteem for girls and women, daughters need to know they will not lose our love if they speak up for what they want to tell us how they feel about things. . . . Teaching girls to make specific requests, rather than being indirect and agreeable, will help them avoid the pitfalls of having to be manipulative and calculating to get what they want.”
—Jeanne Elium (20th century)