Geological terms for easy reference ~ click here

Please note: information on this page is still being formulated and will become clearer over time.  For the meantime I'm jotting things down here for the reference of readers as well as myself.

The terms used to describe and define minerals, rocks and gems and the classes they belong to are particular to the field and not something I'm knowledgeable about; indeed they have been a source of bafflement.  It's a complex subject.  I found the Wikipedia article 'Mineral', linked to above helpful in this respect although still not simple enough for me!  Once I have grasped it better I may write an article about it myself.

For the meantime I'll add in other terms I've found especially useful along with their explanatory links:
  • Lustre: This article outlines the terms used to describe the ways minerals and gems catch and reflect light. 
  • Metamorphic rock: This is rock which is in the process of changing from one form to another.  Change has been brought about by intense pressure deep in the ground before these rocks have been brought to the earth's surface by geological forces.  Quartzite is a good example.  
  • Pseudomorph: a mineral which has moved into another form taking on the existing mineral's structure.  This makes it looks like something that it isn't.  An example of this is tiger's eye in which the host structure is fibrous crocidolite, and the immigrant is silica.  
  • Crystal habit: A fabulously illustrated article which explains terms to do with how crystal formations are described.
  • Silicates: these make up 90 percent of the Earth's crust and all contain silicon and oxygen. 
  • Aluminium: In the Earth's crust, aluminium is the most abundant (8.3% by weight) metallic element and the third most abundant of all elements (after oxygen and silicon).[13] Because of its strong affinity to oxygen, it is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. 
  • Gypsum: was known in Old English as spærstān, spear stone, referring to its crystalline projections. (Thus, the word spar in mineralogy is by way of comparison to gypsum, referring to any non-ore mineral or crystal that forms in spearlike projections.) 
  • Zeolite: This quote from Wikipedia explains the name of this group which is characterised by its ability to absorb  and also release water if heated sufficiently: "the material zeolite, from the Greek ζέω (zéo̱), meaning "to boil" and λίθος (líthos), meaning "stone".[2]"
Later note: this section remains incomplete...  What a fascinating subject this is, and deserving of more time - if only I had it!

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