Soapstone, also known as Steatite, is composed of several minerals. Talc being the most abundant, because of its additives, Soapstone (Steatite) is harder than talc.
The Soapstone that is quarried today is approximately 300 to 400 million years old. Although soft, soapstone is a very dense (non-porous) stone; more so than granite, marble, slate and even limestone.
Since soapstone is impenetrable, it will not stain; no liquid will permeate its surface and for this reason does not need to be sealed. Other stones, including granite, have a propensity to soil; this is why soapstone (steatite) is widely used in chemistry lab countertops and acid rooms.