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We're not just splitting hairs here (hehehehe)
The cleavage of a particular crystal or a type of mineral is critically important to a gemmologist - as opposed to a geologist. This property, along with lustre/er, streak, hardness, transparency etc is what contributes to whether a mineral makes a good gem - or how it should be used as a gem - ie should it be faceted or cabochoned frinstance. (A soft mineral or one that fractures easily will not last long if used in jewellery).
The cleavage of a rock unit however, when looked at in conjunction with its jointing, folding and/or faulting, enables a structural geologist to work out the stress and strain regime required to bring about the deformation. This assists them in working out the the geologicAL history of the district. This enables them to write learned papers, the volume of which is directly proportional to their future scholarship and departmental funding - as well as the likelihood of them attaining a professorial appointment. Occassionally their findings receive application in the real world however, when "proper" geologists - ie exploration geologists - use the information to explain why an economic mineral deposit was found where it was. It's important to note that the learned papers are always written AFTER the deposit has been found - they are NEVER instrumental in the ore body being found. (BTW - this is my first 'white bit' - how'd I go?
Naturally enough, these macro-scale events are usually seen at the micro-scale - ie the rocks' constituent grains are also deformed. Too much deformation would negate their value as a gem.
Now, did I get enough four syllable words in? Very important part of geo-speak those four syllable words. "Phreatomagmatic" is a beauty - it's got six!! Got the taste for white bits now!!
stales
