24 . EXTERNAL CHARACTERS. PARTICULAR GENERIC EXTERNAL CHARACTERS. I. PARTICULAR GENERIC EXTERNAL CHARACTERS OF SOLID MINERALS. 1. THE EXTERNAL ASPECT. The external aspect of a mineral is that outline or con tour which it has received from nature. Thus, if we have a piece of lead glance, as it h$s been found loose, or imbedded in another mineral, we name the surface which it has received from nature its aspect. All those characters which we can discover by the eye on this outline are denominated the exter nal aspect of the njineral. They are of three kinds. 1, The external shape. 2. The external surface; and, 3. The external lustre. 1. THE EXTERNAL SHAPE ’ Is divided into four classes, 1. Common • 2. Particular 3. Regular 4. Extraneous All of these classes have their subordinate differences which we shall no\y describe, and first the external shape. 1. Common external shape, By this we understand the most common and most simple kind of shape, and that which has no resemblance tq any