I found the article I referred to in my previous post.
Here's the scoop:
In California there are 47,000 abandoned mines and 154,800 prospecting pits and tunnels.
Nationwide, abandoned mines have claimed the lives of 91 people since 1991.
The article goes on to say that mines pose three main dangers: horizontal shafts that suddenly become vertical drops, rotting beams that may collapse, and pockets of carbon dioxide.
Abandoned wells can also be a problem. About 10 years ago a camper looking for firewood at night fell 137 feet into a well near Adelanto.
That being said, there are some cool things to see around the Big Horn mine. About 100-200 yards before getting to the mine, turn left on a dirt trail into the old miner's camp. Here you can explore some of the items left behind when the mine was closed. I have found cylindrical core samples, pieces of rock about 2 inches in diameter and 4 or 5 inches long, here as well.