Minerals as a source of our nation’s wealth, 9 descriptive list of, 20-80 regions which offer best inducements to search for, 14 sections of the United States, richest in, 14 species in the United States, how many, 11 specific gravity of, 12, 13 useful in the United States, 11 which will not scratch glass, 16, 19 which will scratch glass 15, 18 Mississippi Valley, 14 Money in the rocks, 9 Nickel, copper, 37 Nitre, 63 localities, 63 value, 63 Nodules, 82 Ochres, 91 Oil wells, 112, 113 Opal, false, how made, 117 the softest of colored gems, 118 Opaque minerals, 12 Ore on a hillside, indications of, 82 veins generally vertical, 82 when it will pay, 92 Ores, assay of, 92-104 minimum percentages of metal in which will pay, 93 Oxyd of Manganese, 63, 64 Pacific coast, 14 Panning, 94, 95 Paris brilliants, 114 Pastes, composition of, 115 Pearls, false, how made, 124 Platinum, 64 localities, 64 value, 64 washing for, 94, 95 Pockets, 82 Precious stones, color and order of hardness, 126 Prospecting for diamonds, 83-87 Pyrites, iron, 53, 54 cobalt, 35 copper, 37, 38, 90 magnetic, 58, 59 testing for gold, 96 yield of gold by, 97 Quartz mining in California, commencement of, 133 ores, yield of, 96 rock, to find the amount of gold in, 98 testing for gold, 95, 96 Quicksilver, use of in assaying, 96 Reading, Pearson B., 131 Read mine, first gold mine worked in United States, 133 Red copper ore, 65 localities, 65 value, 65 hematite, 65, 66 localities, 66 value, 65 silver ore, 66 localities, 66 value, 66 Rennselaerite, 67 localities, 67 value, 67 River sand, worth working for gold, 98 Rock crystal, 67 localities, 67 value, 67 salt, 68 localities, 68 suspected of containing silver, treatment of, 89 Rocky mountains, 14 Ruby, characteristics of, 85 false, how made, 116 spinel, 74 to test, 118, 123 Russia, gold how obtained in, 94 Rutile, 68 localities, 68 value, 68 Saline or salt springs, 109, 110 Salt springs, 110 Sapphire, false, how made, 116 the hardest of colored gems, 118 to test, 118 Searching for copper, 90 diamonds, 83-87 gold, 87-89 iron, 91 lead, 90 silver, 89, 90 Serpentine, 69 localities, 69 value, 69 Shaft, cost of sinking, 83 Silicate of copper, 70 localities, 70 smelting, 101 value, 70