Veins filling the cracks that once existed between two differing rocks are known as contact veins. Such veins are often very rich. Curiously enough large masses of true igneous rock rarely contain valuable deposits of mineral, but where such intrusive masses cut dikes or walls of porphyry, or diorite, the region is worthy of careful investigation. [Illustration: POCKET LENS.] In an open country the prospector should keep to the hill tops if on the lookout for veins, as the outcrops show more distinctly on the bare ridges, but alluvial deposits are only found in valleys and along the borders of streams. In any case, much of the northern part of this continent can only be prospected by following the streams, on account of the dense growth of forest with which the soil is covered. The true line of strike of a vein can be determined only on a level stretch. The line of strike and the line of dip are always at right angles to one another; the outcrop may follow the strike or it may not. A pick, shovel, and pan, are absolutely necessary to a prospector's proper equipment. A good pocket lens, cheesecloth screen, and small iron pestle and mortar are often useful. The pan is the most essential part of the outfit, and is always bright from use. The regular gold miner's pan is 13-3/4 inches in diameter across the top, 10 inches across the bottom and 2-1/8 inches deep. The best are made of sheet iron and have a joint around the bottom rim which is of some assistance in retaining the spangles of gold. A more primitive instrument than the pan is the batea. This requires more skill than the pan, and is much in favor with South American miners. It is made of hard wood, 20 inches in diameter, 2-1/2 inches deep in the center, inside measurement, and sloping gradually to nothing at the sides. The horn spoon has been handed on from antiquity. It is made from a black ox horn, at least a black one is the best as it shows the gold better; it is eight to ten inches long by three inches wide, cut off obliquely. When gold is suspected in quartz, but there is visible to the naked eye more or less iron, copper, and other base metals, it is well to crush the quartz into coarse fragments. Roast on a shovel or other convenient tool over a hot fire, and finally pulverize in the mortar. If panned it will now reveal much of its gold, while, had these measures not been taken, the sample might have given negative results and been declared valueless. After pulverizing, the ore should be passed through the cheese cloth screen before panning. If the approximate value of the ore is sought, the sample must be dried and weighed before crushing; and the resulting gold weighed. Thus: Sample is to 2,000 lbs. as gold found is to Ans.