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the hot invading waters with the ions that result in the telluride minerals. These ions then combine, when deposited in the veins, as tellurides that are the primary minerals of gold. The yellow metal "gold" is secondary after the tellurides. Gold atoms are only transported initially as positive ions in the company of negative tellurium ions (or rarely antimony2 and selenium ions.) The union of these elemental ions is accomplished in an environment of reduced heat and pressure as the brine approaches the crust or near surface environment. This brine is in ionic form; the cation being a positively charged gold ion and the anion is a negatively charged tellurium ion. Deposited as calaverite, in vein fissures, magmatic or plutonic heat then drives the tellurium, anion off and the heat and pressure cause the gold to collapse into what is called "free gold". The collapsing gold then fills the space left by the exiting tellurium and the gold acquires its golden yellow color in the same shape as the original telluride crystal;(some deformation occurs because of the collapse of the gold molecules upon themselves; [a shrinkage in volume.]).It is however; a pseudomorph of gold after calaverite having the same shape and lattice pattern as the original calaverite crystal. This process takes place over thousands or millions of years and it is difficult to compress this scenario into a few short words because there are so many variables. Variables include heat, pressure, chemistry, faulting, various anions, composition of country rock and others. For brevity we will use telluride minerals as the example of choice since it is the most common mineral, along with sylvanite, that this paper addresses. A different pseudomorph of gold is formed when the tellurium is leached away by ground water. The space left by the exiting tellurium is left open and the gold remains as individual atoms / molecules, with no coherent surface to reflect the photons of visible light. Tellurium is the "glue" that holds the gold atoms together in calaverite. Six tellurium atoms surround each gold atom.3 It is the tellurium, surrounding the gold, that gives the telluride minerals the silvery color that is typical of all tellurides. Meteoric waters dissolve and carry off the tellurium in solution. Only ambient ground temperatures are present in this case and the gold does not coalesce into a coherent form, but remains as a porous, friable form in the same shape as the original telluride crystal. Thus the result is a true pseudomorph that differs greatly from those that are transformed by dry heat. The vein contains horn quartz, which is resistant to erosion, and so nodules of horn quartz result as "float", that contain the brown pseudomorphs of gold within the confines of the nodule. A prospector, finding these nodules on the hillside, will know that a rich vein is uphill and somewhere close by. The nodule must be broken open to reveal the pseudomorphs because any evidence of gold on the surface has long since disintegrated into flour gold and left the cavity. Erosional action then, over thousands of years, reduces the vein minerals to earthy material that contains flour gold and stream sorting results in placer deposits that usually contain no nuggets. As always, variations to the theme exist because in mineralogy, nothing is absolute. One variation is the formation of a gossan on the surface of the vein. If the vein is exposed to constant weathering, no gossan will be formed. If the vein is protected by overburden, a gossan will form from the oxidation of iron pyrite into limonite and a rusty crust may form with variable thickness. Inside the confines of the gossan will be found the rounded nodules of quartz and rusty gold. 2 Gold The Noble Mineral, extra Lapis English Nos pp.61-64 Printed in Germany 2003 3 N.D.Sindeeva, Mineralogy and Types of Deposits of Selenium and Tellurium (translated from Russian) pp. 107-108 htterscience publishers, John Wiley and Sons NY 1964 2