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_030 - 2
 

Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires

Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires Page of 251 Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires Text size:minus plus Restore normal size   Mail page  Print this page
18
DE NATURA FOSSILIUM
it is moistened and from which mud can be made when it is saturated with water. True earth may be found in veins and veinlets within the earth as well as on the earth's surface in fields and meadows. Earth is by definition a universal thing. Although the harder earths do not readily form mud when saturated with water nevertheless this is true of even the hardest if they are left in water for a sufficient length of time. There are many species of earth, some of which have been given names.
A congealed juice, called iypos πυκτό$ by the Greeks, is a dry, rather hard mineral body which is either not softened in water but dissolves or, if it softens when sprinkled with water, it differs from an earth in unctuousness or in composition. Although sometimes it has the hardness of stone it can be distinguished with ease since it retains the form and appearance of con­gealed juices which are softer than stone. Congealed juices are divided into harsh and unctuous. There are three species of the harsh because they form from three different things, namely, a liquid mixed with either an earth, a metal, or a mixed substance. In the first we find halite and nitrum; in the second, chrysocolla, aerugo, iron rust, and caeruleum; in the third, atramen­tum sutorium, alum, and an unnamed acid juice. Atramentum sutorium and alum form from pyrite, the unnamed acid juice from cadmia. Unc­tuous congealed juices include sulphur, bitumen, realgar, and orpiment. Although atramentum sutorium and alum may be somewhat unctuous they will not burn. These latter minerals also differ in origin from the unctuous juices. The latter are driven from the earth by the force of heat, the former are produced by the action of moisture on pyrite.
Stone is a dry, hard mineral body that may soften a little after standing in water for a long time and is reduced to a powder in fire or is not softened in water and melts in only the very hottest fire. In the first genus we find stones that have been hardened by heat, in the latter genus those that have been congealed by cold. These two genera are of similar material. Writers on natural subjects who have considered the quantities, qualities and values of stones have divided them into four genera. The first genus, with­out a special name other than the general name stone, includes magnetite, hematite, and agate. Minerals of the second genus are called gems and embrace unusually hard minerals which are either transparent or sparkle with many beautiful colors. Minerals of the third genus are called marbles and these are only pleasing to the eye when polished. Minerals of the fourth genus are called rocks and are obtained from quarries. Rocks are of indispensable use in buildings and in sculpture. They do not show marked colors or take sharp edges. Few stones are lustrous and even fewer are transparent. At times marble cannot be distinguished from non-trans­parent gems except by size or quantity. Rocks can always be distinguished from true stones by size. Gems are found, characteristically, in veins and stringers that run through rocks and marbles. There are many species in each of these four genera which I shall describe later.
A metal is a natural mineral body which is either liquid or solid and will
Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires Page of 251 Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page