Stone sculpture stone carving. Alabaster and softer kinds of serpentine, all about 3 on the Mohs scale, are more durable than soapstone. Alabaster, in particular, has long been cherished for its translucence. Limestone and sandstone, at about 4 on the Mohs scale, are the only sedimentary stones commonly carved. Limestone comes in a popular oolitic variety, about twice as hard as alabaster, that is excellent for carving. The harder serpentines can also reach 4 on the Mohs scale. Marble, travertine, and onyx are at about 6 on the Mohs scale. Marble has been the preferred stone for sculptors in the European tradition
Bishop's Frome Limestone basin between the Silurian and the Devonian periods. The rock was formerly known as the Psammosteus Limestone after a characteristic fossil fish recorded from it; "Psammosteus anglicus". The fossil remains were subsequently shown to have been wrongly identified and belong in fact to "Traquairaspis symondsi". Its modern name derives from the Herefordshire village of Bishop's Frome. Its thickness is variable ranging from 2m up to 8m. Bishop's Frome Limestone The Bishop's Frome Limestone (or Bishops Frome Limestone) is a rock unit within the Raglan Mudstone Formation of the Old Red Sandstone occurring in the border region between England and South