recycled soapstone dangers

A builder friend has offered me free soapStone (http://g603.net) which was used as shelving in a factory he is rehabbing -- he has tons. I'd use it in my kitchen, for Counter (http://GialloFiorito.com) tops. My concern: this was a battery factory, so I must assume the Stone (http://g603.net) has years and (http://maplered.com) years of exposure to lead and (http://maplered.com) other chemicals. I'm trying to figure out if it might be safe to use. Thanks for advice. D.