I've never really thought of Gold as being crystalline, but if it is vaporized and allowed to re-coalesce, it forms as a crystal. In a process, that I won’t even pretend to understand, heat, vacuum, and other chemicals leaches gold from other substances, then allows it form back into 99.99% pure gold. The picture is what the gold looks like when it joins back together. The process is called “The Van Arkle de Boer process”.
The following photo is Platinum formed with a similar process. Iron crystals called "hematite" form at the mouths of volcanoes from a natural occuring chemical/heat process.
|Touchstone for determining gold purity.|
By using a two pieces of gold, of a known quality, to make marks on a touchstone. Then one gold mark of an unknown quality, the grade of the unknown gold can be determined by using mixtures of nitric acid and watching to see which mark disoves first. The term "Acid Test" also comes from determining the quality of Gold. Not being from gold county, I probably seem a little niave to the Mother Lode people.
This blog used to have a commenter by the name of "Gemboy" that knew all of this stuff. I havent heard from him since the post that I did on the Island Mountain Copper mine.