Floris van Breugel / A rock collector explores piles of fluorescent minerals found in the tailings of the Pacific Tungsten Mine near Darwin, California. The bright colours are caused by fluorescence excited by a shortwave...

Juergen Freund / Close up of Giant Stinging Tree hairs on the leaves (Urticastrum gigas or Dendrocnide excelsa). Contact with the leaves or twigs causes the hollow silica-tipped hairs to penetrate the skin. Australia

Gavin Hellier / The Blue Lagoon, Iceland's most famous tourist attraction is located among the black lava flows outside Reykjavik. The geothermal spa owes its existence to the Svartsengi geothermal power plant powere...

Gavin Hellier / The Blue Lagoon, Iceland's most famous tourist attraction is located among the black lava flows outside Reykjavik. The geothermal spa owes its existence to the Svartsengi geothermal power plant powere...

Floris van Breugel / A wide variety of fluorescent minerals including scheelite (blue/white), calcite (red), silica coatings containing uranyl ions (green), fluorite (pink), and 'desert varnish' (yellow/orange), populate...

Yva Momatiuk & John Eastcott / Mine tailings from years of mining for opals near Coober Pedy, South Australia, Australia

Yva Momatiuk & John Eastcott / Mine tailings from years of mining for opals near Coober Pedy, South Australia, Australia

Adrian Davies / Rock crystals containing Chalcedony, from Cornwall, UK

Juergen Freund / Close up of Giant Stinging Tree stem (Urticastrum gigas or Dendrocnide excelsa). Contact with the leaves or twigs causes the hollow silica-tipped hairs to penetrate the skin. Australia

Juergen Freund / Giant Stinging Tree leaf (Urticastrum gigas or Dendrocnide excelsa). Contact with the leaves or twigs causes the hollow silica-tipped hairs to penetrate the skin. Australia

Juergen Freund / Giant Stinging Tree stem (Urticastrum gigas, also known as Dendrocnide moroides or Dendrocnide excelsa) - close-up of the hollow silica-tipped hairs, Australia

Albert Aanensen / Warbrick Terraces algae and silica ,Wamangu Thermal Area, Rotorua, New Zealand

Steven David Miller / Hamersley Gorge in Karijini Natinal Park, showing tectonic bands of iron and silica. Australia

Mark Taylor / Panoramic view of Silica sand bay. Queensland, Australia.

Albert Aanensen / Waimangu Thermal, silica and algae deposit. Warbrick Terraces, New Zealand

Chien Lee / Caves caused by erosion of silica-based rock, Mount Roraima, Venezuela

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