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XVI OF T1IE CHARACTERS OF MINERALS. binations; the countries in which they occur ; and their charac ters, both internal and external. This knowledge, it may be repeated, is the first and requisite step in the science of geology; not that it is essential to this science that every mineral should be accurately known : some are of comparatively little importance in a geological point of view, from their extreme scarcity ; but it is essential to become acquainted with simple minerals in the general, because of some of them, many of the vast masses of the earth are composed. Minerals which are found only in primitive rocks, are said to belong to primitive countries; by which name are designated such tracts as are chiefly composed of primitive rocks. The substance in or on which a mineral is found, is called its gangue or matrix; when in its natural place or position, a mineral is said to be in situ; when this place and position are known, we are acquainted with its habitat. OF THE CHARACTERS 6F MINERALS. § 1. It is one of the first, if not the first inquiry of those w ho are uninstructed in mineralogy', if a specimen, of quartz for in stance, be shown them, how they may recognise it. The reply necessarily is, that it is essential to observe it closely, to study it, to mark with precision its characters;—that as minerals are not organized bodies, their characters are less defined, and therefore not so readily intelligible, as those of such bodies as possess regular organization ;—that, in fact, there is no trea tise, by a reference to which, the beginner is enabled, if he take up a mineral, to arrive at once at a knowledge of its nature ;* that therefore at present practical observation is the only mean of attaining this knowledge. It will be of advantage, then, that these characters, and the mode of observing them, should be pointed out. § 2. Although long experience and attention give a facility in recognising minerals by mere inspection, this facility can only be acquired by such means. There are certain minerals which may at once be detected by some simple experiment; that is to say, there exist a few possessing some one character which de cides with precision what the mineral must necessarily be, be cause that character belongs to no other. For instance, there are three substances which often so nearly resemble each other, that simple inspection indicates no difference, even when re- • The method proposed by Professor Mobs is perhaps the most syste matic, and approaches nearer to this desirable point than any other, . more especially as regards crystalline minerals. K.