Origin of Quartz in References    The reference to Queensland University of Technology Origin of the word quartz is broken in that there is a password requirement to get into QUTconsequently it is useless     Tensile strength  MPa  Pa  Pascals     Pa  pascals  S   There is some controversy over density of quartz Most references Ive found say  gcm see  for details    Abundance of Quartz in crust Quartz is a bit of a pain to write about  Its the most common mineral on earth and occurs in so many different forms  The various names are used to mean different things in different contexts and even then its rarely rigoursly consistant  Ill try and point out some of the range of applicability of the various names and various applicable names  Oh and that density listed is not actually for quartz  Its for fused quartz which is a glass  unlike everyother type of quartz  I suspect that confusion is inevitable whilst it is shown on the main page for quartz    Jan    Actually quartz is not the most plentiful mineral on earth that honour goes to plagioclase I know what youre thinking sediments  of earths crust are  quartz and granitemetamorphic rocks  of earths crust contain about  quartz Right But feldspar is the predominant mineral in granites at  either plagioclase or orthoclase is abundant in metamorphic rocks is also present in sediments and unlike quartz occurs widely in the mafic and ultramafic rocks of the oceanic crust So bzzzt quartz is evicted from the island    although just for fun it does specify continental crust in the article    By the way for my ownerinterest do you have a reference for your backofthe envelope calculation  It sounds very much like you just whipped it off yourself although good for you but if you have a ref that would be great  I have seen other numbers cited in German literature  Cheers   Citrine  Although most citrine occurs naturally most is the result of heattreated amethyst  So what is true about most citrine Is most citrine natural or is most citrine made from amethyst Or is it naturalbutderivedfromamethystoriginally This could stand to be reworded to be less confusing     Fixed  Looks like that was a holdover from an wording change      Pleochroism Its obvious that author of this article doesnt understand the meaning of pleochroism Quartz has absolutely no pleochroism Ill fix it     What is the difference between Quartz and glass   I know that glass is amorphous SiO is the difference just in a macroscopic perspective of how the crystals are arranged or is glas SiO nonpolar while quartz is polar hybridization  Im not sure what youre asking here  do you want to know the difference structurally or how to tell the difference If youre talking identification the best way to tell for sure is to chuck it under a petrology microscope and check to see if its isotropic or not If youre talking structural differences well youre right  glass is amorphous at the atomic level  no regular lattice at all    History of Quartz  The exact date place and creator of the quartz oscillator are unknown to the public as this information is classified It is believed that it may eventually become public as the aftermath of the Cold War wears off   Walter Guyton Cady created the first Quartz crystal resonator along with other colleagues at Wesleyan University in Middletown Connecticut in    George Washington Pierce also help future work in quartz oscillation by designing different types of quartz oscillators    Warren Marrison a telecommunications engineer developed the first quartz clock in  based on Cady and Pierces work at Bell Telephone Labratories  httpwwwhrwcomsciencesisciencechemistrycareersquartzinventorsbeforehtml   Thanks I have modified the article based on your reference    September