Jim Brandenburg / American Bison (Bison bison) herd on prairie with quartz, Blue Mounds State Park, Minnesota

John Cancalosi / Brazilian agate, slice, with MR. Sad Face design.

Niall Benvie / Close-up of quartz vein in rock, abstract. Scotland, February.

John Cancalosi / Quartz (SiO2, silicon dioxide), the most common mineral on earth, used in making glass and other industrial uses.

Jack Dykinga / Eroded formation known as the 'Tres Maries', in the Valle de la Luna. One million year old composition of gravel, clay, salt, gems and quartz, against The Milky Way and Southern Cross in the night sky...

Jack Dykinga / Eroded rock formation known as the 'Tres Maries', in the Valle de la Luna. One million year old composition of gravel, clay, salt, gems and quartz, against The Milky Way and Southern Cross in the nigh...

John Cancalosi / Azurite-malachite rock slab, cut and polished, white quartz with veins azurite and malachite copper minerals, occurs in copper-bearing rocks in central Siberia. Stepnoye Mine, Altay Mountains, Siberia...

Heather Angel / Quartz-sanstone pillars covered with Wulingyuan pine trees (Pinus spp). Zhangjiajie National Forest Park, Wulingyuan Scenic Area, Hunan Province, China.

Jack Dykinga / Titus Canyon conglomerate and quartz formations, Death Valley National Park, California, USA, March 2019.

Graham Eaton / Triassic age Conglomerate and Sandstone, part of the Otter Sandstone Formation. The conglomerate pebbles mostly comprize quartz and quartzite reaching 20cm in diameter. Budleigh Salterton, Devon, UK,...

Graham Eaton / Quartz infilled tension cracks in a boulder on the beach. Millock Haven, Cornwall, UK, March

Graham Eaton / A Tertiary age dolerite dyke intruded into foliated, Pre-Cambrian age quartz mica schist near Rhosneigr, Anglesey, Wales, UK, June