All limestone rocks consist of nothing but the aggregated ... and warned medical men in making chemical examinations of the dead bodies of persons supposed to have been poisoned, to bear this ...

Mysterious tunnels in desert rocks may be the work of unknown microbes, hinting at a hidden world inside marble and limestone ...

Mysterious micro-burrows in desert marble and limestone were probably made by microbes that lived millions of years ago. Exactly what kind of microbes bored into the rock remains unknown, as does ...

Minerals are chemical compounds which occur naturally ... Marble is formed from limestone (a sedimentary rock) and contains tiny interlocking grains. This makes it very smooth and can be polished ...