Mali kids dig for gold for bags of dirt

>>> it's the holiday season and a lot of people are buying gold jewelry this time of year. the commercials show us the joy on christmas morning but they don't show us the work that goes into getting the gold out of the ground. getting at it is dirty and dangerous and in some places children are doing the work. later tonight on "rock center" we are going to air an investigation by richard engel who went to mali to can check for himself.

>> i'm going down. let me check the rope first.

>> reporter: the first couple of steps look easy with carved footholes to go down. but 20 feet down the footholds stop.

>> no more footholds. i'm pushing my weight against the other side and using the rope a little bit. okay. almost there. i finally made it to the bottom. there are six workers down here with picks chipping into the rock. there are some very, very primitive wooden supports to try to keep this mine apart. aside from the rock, the rest of the is surface is just soft mud and a big concern, at least that i have, is that this mine could just collapse. is there gold in this? [ speaking in a foreign language ]

>> reporter: are you sure? there's gold in this? there goes the bag. i hope it doesn't, but i'm very worried that this mine is going to collapse on you. i'm going to get out of here.

>> happy to report richard engel is back with us in studio.

>> 12% of the world's gold comes from mines like that one that are dug by hand. in mali alone, 20,000 to 40,000 children work in these mines. many of them are also poisoning themselves because they use tremendous amounts of mercury which binds with the gold ore. it leaves mali , goes to the international market , is melted down and becomes anonymous. later tonight we'll discuss where it ends up.

>> you can see richard's reporting on the story tonight here in the studio on "rock center" at 10:00 eastern time . now on our website, today.com.