It has been observed that fissure veins show some signs of motion or slipping on the sides of the fissure such as slickensides or crushed walls, and small portions of the rock are surrounded and cemented by a vein. The recognition of gold is important, and more even when the veins itself, though occupying a healed fault fissure, may be itself faulted. Basically, a vein filled fissures being a line of weakness, may be reopened by mountain movements and other or different combinations of ore introduced into the heart of the vein. Such a reopening may be marked by a succession of combs or banded ribbon-like deposits of ore.
Basically, the outcrop of a vein is that which appears at the surface and usually attracts prospectors to the spot. Sometimes it may be a bold vein of hard white or rusty quartz, standing up in relief, by its superior hardness above the surrounding rock like a wall. In some cases, it may be composed of softer or more soluble substances than the prevailing eruptive lava sheets, instead of a wall causes a depression or through on the side of a hill forming the pathway for a creek. The outcrop consists of a decomposed mass of rock, stained with iron oxide and streaked. In some occasions, the presence of oxide copper mineral is noted. The stained zone is the chemically modified or oxidized portion of the vein lying deeper below the soil.
In gold veins such as an oxidized condition is desirable if it continues down to any depth, for, so far as it continues, the gold is free and the ore is a free milling ore in some occasions, easily treated and often exceedingly rich in gold. When the hard white quartz and the unoxidized pyrite of the vein is reached, the ore is not more free milling. The gold may be found free, in the hard quartz, but if the pyrite has no gold, the rich ore found could be a small spot. Many gold deposits on the surface present abounding specimens of free gold, which no necessarily follow the same trend with the depth.
All veins do not carry gold in the same concentration or minerals and may be just quartz, feldspar or calcite like extremely low gold grade spots traversing limestone rocks. Veins may divide or thin out, and are irregular in shape and structure due to the irregular width of the fissures.
Recognition of gold in fissure veins