Blue masses of azurite are formed from the weathering of copper minerals. Used as a pigment by Renaissance painters. Image #2278 3033 X 4329 pixels
Metamorphic rock formed by the serpentine group of minerals; Washington State Image #2555 4800 X 3200 pixels
Macrophotograph of the structural detail in a pietersite gemstone from Arizona. Also known as 'Arizona tiger eye' it is a variety of chalcedony that contains amphibole mineral fibers that result in a chatoyant (optical reflectance) effect. 4080 X 6144 pixels (7.77 MB)
