I was talking to a friend who has experience dredging gold (he still has two claims in California), and he mentioned that if you want to smelt your raw gold you need a federal license. I vaguely remember reading about this in the past, but can't turn up any current references on the topic. So, what is the deal, can you melt your nuggets to consolidate them or do you need a license? If so, what is involved getting one?
Effective Jan 1, 1975, that is no longer true. Prior to that date, it was illegal to melt or otherwise process gold without a federal license under penalty of $10,000 fine and 10 years in prison, as I recall. There are currently no regulations pertaining to the ownership or processing of gold.
What reason does this person have for melting his gold? It does little in the way of purifying it, and may be destroying gold found in the natural state that has value beyond refined gold. Specimens are almost always in demand, assuming they are of reasonable size. Fine bits tend to be worthless beyond the value of the gold and other contained values.
Gold it typically alloyed with silver, and occasionally copper, along with other elements, including arsenic. In order to convert it to useable metal, it should be properly refined. While that's not beyond the capability of the home type refiner, it does require a little knowledge prior to getting started.
Sadly, when you melt gold found in nature, especially if it runs low in gold (less than 90%), melting it usually results in some pretty ugly material. Pure gold has a wonderful color and luster, which is readily lost when alloyed, When the alloys are dirty, such as are typically found in nature, it's not unusual for the gold to turn out frosted and dull in appearance. The nuggets have been abraded and mauled, plus aged (for coloration) such that they tend to be far more attractive. I'd recommend you friend either enjoy what he has the way it is, or learn refining techniques and purify the metal before casting a common bar.