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_099 - 2
 

Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica

Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Page of 251 Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Text size:minus plus Restore normal size   Mail page  Print this page
BOOK V
87
Sulzbach. In any locality where one finds hematite and schistos one will also find red rocks and earths from which, as a source, these minerals are formed. Dioscorides writes that hematite is found in the red ocher of Sinope. Schistos occurs in Spain, hematite in Arabia, Egypt, Africa and Ethiopia.
Each mineral varies in color. They may be similar in color to dried blood, hence the name, or they may imitate the color of iron and at times the surface may even have the color of saffron. The latter material is found in Misena. A variety that is entirely black is mined not far from the mountain named for the silver birch, as I have just mentioned. Sotacus relates that a variety of black schistos is found in Africa and from its resemblance to quenched coal is known as anthracites. Schistos is usually smooth on the outside and as brilliant as polished iron, for example, that from Misena which is the hardest of all. It is less brilliant inside. Some is not brilliant externally but sparkes on the inside like the artificial mini­um the painters call cinnabaris. Mineral of this variety occurs in the Harz forest. This same material, when pulverized, sparkles as though it had been adulterated with mercury.
I shall now take up the colors produced by both of these minerals when rubbed on flint and the colors they have after being burnt. Some produce a streak with ease, as is usually the case, while others, for example the material from Arabia and Misena, give a streak with difficulty because of their excessive hardness. Although they commonly give a blood-red streak the material from Africa called anthracites gives a black streak from the bottom portion and a yellow streak from the rest. Similarly the ma­terial from Goslar that has congealed in the form of grapes gives a black streak from one part and a dark yellow streak from another. The Arabian hematite has a color similar to saffron. Both schistos and hematite, if they have congealed with a color similar to blood, imitate the color of cinnabar after they are burnt and if they are black burning will deepen the color. Burning turns all other varieties of schistos to a florid color. Both hematite and schistos draw the tongue together. Although each is dense and usually hard the more the luster of schistos approaches the luster of iron the harder it is, for example, that found in Misena and the Harz forest. Some knots are found in Misena the size of walnuts and so hard that when placed upon an anvil they are unaffected when struck. Silversmiths polish these hard pieces and then, in turn, use them to polish very thin pieces of gold foil by drawing the foil over the stones. They also use them to polish the foils they place beneath gems in order to improve the color of the gem with the color of the foil. In each case the stones are fashioned into various shapes.
Hematite almost always occurs in the form of lumps and may be full of little hollows as is that from Hildesheim. The Harz mineral sometimes congeals in the form of grapes. Schistos shows a much greater variety of forms. It may be wedge-shaped at either end or both. Sometimes it is
Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Page of 251 Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page