These are images of a stone found and used extensively in the Jammu & Kashmir region between India and Pakistan. These are called devir or devri in the local parlance.

Following is the description of the stone according to one website that I looked up:

Devri stone is an impure lime stone extracted from earth at various parts of the Kashmir. The stone is soft in its nature and gives white appearance after carving. The stone can be molded to any form or shape.

I am planning to write a research paper on 'hamam' which is an underfloor heating system used in the kashmir valley, devri stones are commonly used as the floor surface for the hamams. I would like to know if there is an globally accepted name for this type of stone, so that I can report that in my paper. Also, it would make easy for me to acquire scientific data about these stones.