Composition
The overwhelming bulk of these meteorites consists of the Fe,Ni-alloys kamacite and taenite. Minor minerals, when occurring, often form rounded nodules of troilite or graphite, surrounded by schreibersite and cohenite. Schreibersite and troilite also occur as plate shaped inclusions, which show up on cut surfaces as cm-long and mm-thick lamellae. The troilite plates are called Reichenbach lamellae.
The chemical composition is dominated by the elements Fe, Ni and Co, which make up more than 95%. Ni is always present; the concentration is nearly always higher than 5% and may be as high as about 25%. A significant percentage of nickel can be used in the field to distinguish meteoritic irons from man-made products, which usually contain lower amounts of Ni, but it is not enough to prove the meteoritic origin (e.g. some US coins).
Read more about this topic: Iron Meteorites
Famous quotes containing the word composition:
“Give a scientist a problem and he will probably provide a solution; historians and sociologists, by contrast, can offer only opinions. Ask a dozen chemists the composition of an organic compound such as methane, and within a short time all twelve will have come up with the same solution of CH4. Ask, however, a dozen economists or sociologists to provide policies to reduce unemployment or the level of crime and twelve widely differing opinions are likely to be offered.”
—Derek Gjertsen, British scientist, author. Science and Philosophy: Past and Present, ch. 3, Penguin (1989)
“If I don’t write to empty my mind, I go mad. As to that regular, uninterrupted love of writing ... I do not understand it. I feel it as a torture, which I must get rid of, but never as a pleasure. On the contrary, I think composition a great pain.”
—George Gordon Noel Byron (1788–1824)
“Every thing in his composition was little; and he had all the weaknesses of a little mind, without any of the virtues, or even the vices, of a great one.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)