139) Page 248: Quartz (amethyst variety), Erongo Mountains, Namibia * 5 x 6 x 3 cm Page 251: Calcite, Irai...Serbia ¢ tixex7 cm LEFT: Fluorite, Taihang Shan Mountains, Hebei, China * (Sexes selem 10 | MINERALS:...considered to be minerals. Microcline, Crystal Peak, Colorado, USA * 12 x 9x 5 om MINERALS: PRODUCTS OF A...A CHANGING PLANET 11 Vanadinite, San Carlos district, Chihuahua, Mexico * 8 x 4 x 2 cm Mineral Species...zeolites. Calcite (septarian nodule), San Juan County, Utah, USA * 18 x 24x Bem 14 | MINERALS: PRODUCTS |