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Post by Jaga on Dec 14, 2008 8:00:58 GMT -7
What is a name of a rock, which does not have any minerals and is very common in Poland?  not an easy question. I did not know until today. If you do not know I will give some hints later on |
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Post by Drohojowski on Dec 14, 2008 9:37:45 GMT -7
Do you mean a true rock? There are fossils like amber and glasses like obsidian that don't contain minerals. Otherwise, I'm not sure....
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Post by Jaga on Dec 14, 2008 10:00:34 GMT -7
My thought would go exactly the same way you go.
Hint - if something if of organic origin it is not a mineral, so this rock is very black
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Post by Drohojowski on Dec 14, 2008 10:27:02 GMT -7
I really have no idea. Your hint suggests coal to me, but coal certainly undergoes mineralization. I would guess pumice or scoria, since they are rocks that are usually comprised of glass grains and would therefore lack minerals. Probably more knowledgeable minds should have a guess....
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Post by Jaga on Dec 14, 2008 11:13:48 GMT -7
It is a coal since it has only organic origin. One of the definitions of mineral is that it is inorganic. If you think about coal which did not go through any metamorphosis - this is just an aggromerate of grains with some organic staples
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Post by Drohojowski on Dec 14, 2008 12:00:44 GMT -7
Hmm... well, alright, I certainly take your point. But isn't coal sedimentary in nature such that even though the principle makeup of coal is organic plant matter, it does contain minerals deposited in the component sediment as well? I like the answer, and I had no initial notion that was the case, but I would also consider the various igneous rocks comprised of glass particles, i.e., pumice and scoria which are, in the purest states, devoid of minerals, too.
Did that come from that Wikipedia list you mentioned? I remember reading the post about a list of lesser known things or something of the sort.
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