Güirisería in RAAN
Upside Down World has a great article on güirisería, artisan mining in RAAN. While there is commercial mining inNicaragua, this article is about artisan mining in the the Siuna/Rosita/Bonanza area. This is about as local and low-tech as you can get.
The article is full of pictures to help explain the artisan mining process. Note that while one might think this process which has been going on since 1880 in the region is not as dangerous to people and the environment, that isn't the case. This is also explained in the article.