Gold Aquamarine how does the way gold is formed affect the way gold is mined? and: why do emeralds cost more than aquamarines?
The pricing of gemstones is somewhat arbitrary, but it does have to do with how rare the stone is. Although emeralds and aquamarine are both varieties of the mineral beryl, it is much harder to find quality emeralds than it is to find quality aquamarine. Also, aquamarines can occur in very large stones (weighing several pounds, even), much larger than any emeralds. I wish aquamarines were as valuable, because I find those at my mine.
I'm not sure about what you're asking in the gold part of the question, but typical gold deposits can be free gold in quartz, placer gold in sedimentary deposits, or gold as a byproduct of other mining, such as copper. Gold in quartz is usually mined by excavating the ore, crushing it to free the gold, and then using a density separation technique such as washing the crushed ore over riffles. Similar techniques are density separation techniques are used for placer gold, although if it is a stream deposit then sluice boxes may be used. Gold in other ores is usually recovered during the process of the other ore.