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_130 - 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
118
DE NATURA FOSSILIUM
forated in order to make it more attractive by removing the whiter mar­row. When gold is added, according to Pliny, the beauty of this gem is improved since much of its brilliancy may be lost when it is thick.
I shall now discuss the form of gems, both the natural form and that given to them by artisans. There is a great variety of forms. They may be round like a sphere or hemisphere; sometimes solid, sometimes hollow. Some are angular and the angles either project or are fiat and level. When a diamond has a natural hexagonal form, and this is the most highly prized, it is set in a ring in such a fashion that a sharp point projects from the setting. If it is oblong or rounded like a shield it is cut to a hexagonal form, as are all other gems, but the angular portion is set in the ring while the flat portion stands above the setting. This form which is given arti­ficially to all transparent gems is most highly esteemed. The next most popular form is the oblong gem with facets that are all equally prominent. Lens shaped gems are less popular. Least popular are gems that are rounded like a shield and of these the solid gems are more popular than the hollow ones. It is possible to give a hexagonal form to the solid ones, not to those that are hollow. In some districts valuable gems are found while in other districts gems of the same form are valueless. Nevertheless among the valuable gems some worthless ones are always found and like­wise among worthless gems some valuable ones may be expected.
Since gems may be classified chiefly by color, I shall speak first of the (colorless) ones. The Greek name for quartz comes from its close resem­blance to ice and the Latins have translated the Greek name into their own language and call it crystallus.7 Indeed certain people believe that quartz is ice, i.e., rain water that has been solidified by extreme cold, but this is not true. It is actually a juice that has been congealed by cold. If it were water solidified by extreme cold it would be most abundant in regions where extreme cold prevails, where the brooks and even the largest rivers are frozen to the bottom and it would melt when brought into the warm sunlight. Both are contrary to facts. Not even the ice on the highest Alps which has become hard from the perpetual cold which has existed there for years, actually hundreds of years, is changed into quartz. Even this ice, although it may be hard as stone, melts when it falls from the heights into the warm sunshine. We must conclude that quartz is a juice which, as I have written in De Ortu & Causis Subterraneorum, has been coagu­lated by the cold within the earth and for that reason has been found in openings in marbles and rocks. Sometimes it is turned up by the plow and it may be carried along by streams but in each case it has come originally from veins or stringers. Actually, when a crystal projects outward from the rough rock, as can be observed in the Alps and the highest part of Mt. Melibocus, it is certain that the force of the waters has washed away the minerals that were around it. Those who gather these from inaccessi-
7 Greek, κρύσταλλοι from Kpbos, icy cold, frost.
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