Soapstone is not formed from a single sedimentary rock type. Instead, it's a metamorphic rock, meaning it's formed when existing rocks are transformed by heat and pressure.

Soapstone originates from talc-rich sedimentary rocks like shale or dolostone. These rocks are composed of minerals like talc, chlorite, and serpentine, which are then altered by heat and pressure during the metamorphic process.

Here's a breakdown:

* Original Rock: Shale or dolostone (sedimentary rocks)

* Transformation: Heat and pressure (metamorphism)

* Resulting Rock: Soapstone (metamorphic rock)

The talc in the original rocks is what gives soapstone its characteristic soft, smooth texture and soapy feel.