You have found what you think is a diamond, Does the specimen scratch glass? Yes, easily, and is brittle. Can you see through it? You say it is clear as glass. Look now under section A, “translucent” series, number 6 (for it is colorless), and decide which of the four it is. The first one (27), is diamond; but do not let your wishes _make_ it agree. Turning to the description, you read that it can not be scratched with a file or worn down on a grindstone. This decides against it. Besides, the gravity (2.5) is too little. With the next (57) it agrees perfectly, and you need not go further. Should the specimen, however, agree very well with rock crystal, only that its gravity (3.5) is too great, then it is topaz. ☞ All minerals that scratch glass are brittle, and all (save 32 and 46) are infusible or melt with great difficulty. ☞ The following minerals will burn, evaporate or melt without a flux in an ordinary fire: Nos. 2, 4, 5, 7, 10, 13, 14, 16, 18, 19, 21, 23, 24, 26, 29, 33, 35, 37, 44, 53, 55, 62, 63, 70, 71, 75. All but the following are heavier than marble: 2, 4, 6, 7, 10, 14, 16, 34, 36, 40, 47, 48, 56, 60, 61, 69, 71. Nos. 2, 50 and 58 alone dissolve in water. ☞ In determining color, be sure you have a fresh surface, for the outside is often deceptive. By “blow-pipe” is meant the tapering tube used by watch-makers. A. WILL SCRATCH GLASS. I. OPAQUE. (1) Black: 12, 20, 28, 30, 42, 43, 51, 54, 67, 72. (2) Brown: 12, 28, 42, 59, 72, 77. (3) Red: 39, 46, 54. 59. 67. (4) Yellow: 38, 72, 77. (5) Gray: 22, 28, 72. (6) White: 64. II. TRANSLUCENT. (1) Brown: 32, 59, 72, 77. (2) Red: 17, 32, 46, 59, 68, 73, 74. (3) Yellow: 32, 59, 72, 73, 77. (4) Green: 74, 77. (5) Violet-blue: 3. (6) White: 27, 57, 73, 77. (7) Banded or clouded: 1. B. WILL NOT SCRATCH GLASS. I. OPAQUE. Harder than white marble.[2] | Softer than white marble. | (1) Black: 11, 35, 47. | 4, 7, 10, 12, 13, 14, 16, 24, | 34, 37, 49, 51, 55, 56, 76. (2) Brown: 66, 75. | 12, 14, 21. (3) Red: 44, 53, 75. | 21, 23, 41, 55. (4) Yellow: 26, 44. | 12, 33, 56. (5) Green: 45. | 60, 61. (6) Gray: 35, 66. | 5, 24, 31, 34, 36, 49, 56, 63, | 69. (7) White: 6, 9, 11. | 36, 40, 56, 62. II. TRANSLUCENT. (1) Black: 11. | 55. (2) Brown: 9, 11, 65, 66. | 48. (3) Red: 9, 11, 18, 53, 78. | 36, 55. (4) Yellow: 9, 11, 15, 29, | 48, 71. 47, 78. | (5) Green: 29, 45, 65, 70. | 48, 60, 61. (6) Blue: 8, 18, 29, 47. | (7) Gray: 19, 47, 65, 66. | 37, 69. (8) White: 18, 47. | 2. (9) Mottled or Banded: 47. | --------------------------------+---------------------------------- CHAPTER III. DESCRIPTIVE LIST OF USEFUL MINERALS.