Graham Eaton / Pebbles of semi-precious Jasper, Quartz SiO2, in shingle on a beach, Aberdaron, Wales. The jasper is present in the rocks associated with an ancient plate boundary. July

Albert Lleal / Emeralds in rock, Belgium

John Cancalosi / Aquamarine, gemstone variety of the mineral Beryl (beryllium aluminum silicate), precious stone, Pakistan

John Cancalosi / Azurite (copper carbonate), a minor ore of copper and used as gemstone and ornaments. Sample from Malbunka Copper Mine, Areyonga, Northern Territory, Australia.

John Cancalosi / Kunzite, ore of lithium. It is a pink to light purple variety of the mineral spodumene. Discovered in 1902 and named after geologist George F. King. Only popular as a gemstone since the 1990s, Used as...

John Cancalosi / Spessartine Garnet (Mn3Al2Si3O12) with Smoky Quartz (SiO2) (single crystal) and Feldspar (pink), from Fugian Province, China. Used primarily as a gemstone and as a collector's specimen

Graham Eaton / Opal, hydrated silica, SiO2 nH2O, from Australia