Chapter V., and the particles of gold are not heavy enough to remain at

the bottom but float away, the bed will not pay.

Along streams rather high up among the mountains, and in the gravelly drift covering the slopes of the valley below, are the best prospects. Where the stream meets an obstacle in its path or makes a bend or has deep holes, there we may look for “pockets” of gold. Black or red sands are usually richest. Gold-bearing rock is a slate or granite abounding in rusty looking quartz veins, the latter containing iron pyrites or cavities. Almost all iron pyrites and silver ores, may be worked for gold. When the quartz veins are thin and numerous rather than massive, and lie near the surface, they are considered most profitable. Few veins can be worked with profit very far down. As traces of gold may be found almost everywhere, no one should indulge in speculation before calculating the percentage and the cost of extraction. Gold-hunting, after all, is a lottery with more blanks than prizes.

The substances most frequently mistaken for gold are _iron pyrites_, _copper pyrites_ and _mica_. The precious metal is easily distinguished from these by its malleability (flattening under the hammer) and its great weight, sinking rapidly in water.

SEARCHING FOR SILVER.--This metal is usually found with lead ore and native copper. Slates and sandstones intersected by igneous rocks as trap and porphyry, are good localities. Pure silver is often found in or near iron ores and the dark brown zinc blende. The Colorado silver lodes are porous at the surface and colored more or less red or green. Any rock suspected of containing silver should be powdered and dissolved in nitric acid. Pour off the liquid and add to it a solution of salt. If a white powder falls to the bottom which upon exposure turns black, there is silver in it. Silver mines increase in value as in depth, whereas gold diminishes as we descend.

SEARCHING FOR COPPER.--The copper ores, after exposure, or after being dipped in vinegar, are almost invariably green on the surface. They are most abundant near trap dykes. The pyrites is generally found in lead mines, and in granite and clay-slate. Copper very rarely occurs in the new formations, as along the Atlantic and Gulf borders, and in the Mississippi Valley south of Cairo.

SEARCHING FOR LEAD.--Lead is seldom discovered in the surface soil. It is also in vain to look for it in the coal region and along the coast. It must be sought in steep hills, in limestone and slate rocks. A surface cut by frequent ravines or covered by vegetation in lines, indicates mineral crevices. The galena from the slate is said to contain more silver than that from the limestone. The purest specimens of galena are poorest in silver; the small veins are richest in the more precious metal. A lead vein is thickest in limestone, thinner in sandstone and thinnest in slate.

SEARCHING FOR IRON.--Any heavy mineral of a black, brown, red or yellow color may be suspected to be iron. To prove it, dissolve some in oil of vitriol and pour in an infusion of nut-gall or oak-bark; if it turns black, iron is present. If a ton of rich magnetic ore costs more than $4 at the furnace, good hematite more than $3, and poor ores more than $1.50 or $2, they are too expensive to pay, unless iron is unusually high. Deep mining for iron is not profitable. Generally speaking, a bed of good iron ore, a foot thick, will repay the cost of stripping it of soil, etc., twelve feet thick. Red and yellow earths, called ochres, contain iron. Magnetic ore is easily found by a compass.