I found this article interesting and will post a couple excerpts below that you may be able to compare to SLI.
1)Finding gold can take years. A large gold deposit was found recently in the Baoxinggou mining area, in Tahe, by Zhang Zhao's corps. The survey started in 2002. The key to this particular discovery was that about 24 grams of gold were discovered in a 1-ton rock.
2)
This rock indicated that the area had rich deposits.
http://www.chinamining.org/News/2012-08-14/1344908461d58656.html