Formation
Nuggets are gold fragments weathered out of an original lode. They often show signs of abrasive polishing by stream action, and sometimes still contain inclusions of quartz or other lode matrix material. A 2007 study on Australian nuggets ruled out speculative theories of supergene formation via in-situ precipitation, cold welding of smaller particles, or bacterial concentration, since crystal structures of all of the nuggets examined proved they were originally formed at high temperature deep underground (i.e., they were of hypogene origin). Other precious metals such as platinum form nuggets in the same way.
Read more about this topic: Gold Nugget
Famous quotes containing the word formation:
“I want you to consider this distinction as you go forward in life. Being male is not enough; being a man is a right to be earned and an honor to be cherished. I cannot tell you how to earn that right or deserve that honor. . . but I can tell you that the formation of your manhood must be a conscious act governed by the highest vision of the man you want to be.”
—Kent Nerburn (20th century)
“Out of my discomforts, which were small enough, grew one thing for which I have all my life been grateful—the formation of fixed habits of work.”
—Elizabeth Stuart Phelps (1844–1911)
“The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.”
—Aristotle (384–322 B.C.)