. The prospector's field-book and guide in the search for and the easy determination of ores and other useful minerals. amid. The tetragonal system has also three axes as inthe isometric, and they are at right angles to eachother, but the vertical axis is longer than the others,as in Fig. 16. The term tetragonal means four-cornered or an-gled, and is not precise, for a cube is tetragonal,but it is used to express this form because it is oneword; otherwise square prismatic would be amore correct description, since Fig. 16 is that of a 62 PROSPECTOR S FIELD-BOOK AND GUIDE. prism; for in mineralo
. The prospector's field-book and guide in the search for and the easy determination of ores and other useful minerals. amid. The tetragonal system has also three axes as inthe isometric, and they are at right angles to eachother, but the vertical axis is longer than the others,as in Fig. 16. The term tetragonal means four-cornered or an-gled, and is not precise, for a cube is tetragonal,but it is used to express this form because it is oneword; otherwise square prismatic would be amore correct description, since Fig. 16 is that of a 62 PROSPECTOR S FIELD-BOOK AND GUIDE. prism; for in mineralogy any crystal having paral-lelograms for sides is called a prism. Cut thisprism as in the case of the cube, and you will havethe form seen in Fig. 17. Variations upon this form may show a prism withfour-sided termination at either or both ends, as inFig. 18. This is the form of the transparent gemcalled the zircon, anciently called the jacinth. Thezircon has been mistaken for the diamond, which itresembles in brilliancy, and somewhat in the diamond is isometric and never tetragonal, Fig. 16. Fig.
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