I work primarily in Mt Gambier Limestone.  Here is a little information about it:

• ​It is a coralline limestone found in the south east of South Australia.
• It was formed over 30 million years ago, from deposits of lace coral, when the region was under the ocean.
• There are occasionally shells and fossils in the stone, although it is generally very consistent in texture making it suitable for carving.
• It is quarried for the building industry in the form of blocks called ashlars.
• The material is very soft, making it easy to carve, but despite this softness it lasts very well outside, particularly when coated with a sealer.

Some photos from the Quarry