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Minerals Reference Libraries

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Chert
2005-05-26 11:30:45

Chert is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. It varies greatly in color from white to black, but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced...

Limonite
2005-05-26 09:37:09

Limonite Limonite is a ferric hydrate of varying composition, the generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as Limonite often contains a varying amount of oxide compared to hydroxide. Together with hematite, it is mined as ore for the production of iron. Limonite is heavy and yellowish-brown. It is not a true mineral, however, but a...

Word of the Day
sough
  • A murmuring sound; a rushing or whistling sound, like that of the wind; a deep sigh.
  • A gentle breeze; a waft; a breath.
  • Any rumor that engages general attention.
  • A cant or whining mode of speaking, especially in preaching or praying; the chant or recitative characteristic of the old Presbyterians in Scotland.
  • To make a rushing, whistling, or sighing sound; emit a hollow murmur; murmur or sigh like the wind.
  • To breathe in or as in sleep.
  • To utter in a whining or monotonous tone.
According to the OED, from the 16th century, this word is 'almost exclusively Scots and northern dialect until adopted in general literary use in the 19th.'
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