Quantcast
  Due to a new server, slow response may occur for which we apologize Portal logo
Login/Register
Bactrian Gold Treasure from Afghanistan, coming soon....
/gemstones/agricola_textbook_of_mineralogy/page_131 - 2
 

Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis

Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis Page of 251 Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis Text size:minus plus Restore normal size   Mail page  Print this page
BOOK VI
119
ble rough rocks commonly, according to Pliny, hang from a rope. It is also found in metalliferous veins and veins of the pure mineral. It occurs in many places, in Spain, France, Germany, the Alps, Scythia, Cyprus, Asia, Carmania, India and on two islands in the Red Sea near Arabia, one island being called Neron, the other Chitis.
The best quartz is colorless and as transparent as limpid water. Flaws are common, those that have a color are spotted or similar to black clouds while those that have a body resemble scales, "salt," ulcers, hairs, rust, iron rust and lead rust. Sometimes quartz crystals contain silver minerals of a lead or reddish color (probably argentite and proustite). The former is the more valuable and the best. The silver is usually in the body of the quartz, rarely on the end.
Quartz crystals vary in size and consequently in weight. While the shortest crystals may be less than half an inch high Juba writes that he remembers a crystal eight inches long that was dug up on the island of Chitis by Pythagoras, prefect of king Ptolemaeus. Crystals may be less than a quarter of an inch thick yet Pliny describes a crystal found in India that was so thick that a vase which could hold three quarts of liquid was cut from it. Xenocrates describes a vase similar to an amphora cut from a single crystal. While the smallest crystal may weigh only a scruple, Pliny writes that Livia Augusta placed one in the temple to Jupiter which weighed approximately fifty pounds.
Quartz crystals are rarely found single. Usually a number occur together growing from a common base, sometimes standing up separately, some­times united. Some crystals stand vertically, some are inclined, some lie on the base adhering to it so that they cannot be removed easily. Some­times a number grow on a common base and are so united that they can only be separated with the greatest difficulty. A single large and perfect crystal may form surrounded on all sides by many small and imperfect crystals which are seen to have only three sides as if they were half crystals since quartz is hexagonal although the sides are usually unequal. Quartz crystals often have two broad and four narrow sides while rarely there are four broad and two narrow sides. Moreover a narrow side may taper and a broad side become broader.
The sharp termination of the crystal is hexagonal similar to the body. The point differs in that the narrow pyramid is not always above the nar­row side and sometimes the broad pyramid may be above the narrow side. Only a small portion of the mass of the crystal is in the point, the greater part being in the angular body although some crystals found on the cliffs of Blocheberg have a large point and a small body. The faces of the point are so much smoother than those of the rest of the body, unless they contain flaws, that they can be polished only with great effort.
Since quartz cannot withstand heat, cold liquids can be poured into quartz goblets without injury to them but if a hot liquid is poured into them they break. Not only are goblets made from this mineral, such as
Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis Page of 251 Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page