(19) Rebecca Calhoun.. CC-BY-SA.
(20) Eric Hunt.
http://en.wikipedia.org/wiki/Image:Azurite_from_China.jpg,http:
//commons.wikimedia.org/wiki/Image:MoreMalachite.jpg. CC-BY,Public
Domain.
(21) Stepanov Alexander. This diamond mine is more than 600 m deep.. GNU-FDL.
(22) You can use the properties of a mineral to identify it.. CC-BY.
(23) CK-12 Foundation.. CC-BY-SA.
(24) David Jones.
http://commons.wikimedia.org/wiki/Image:White_Sands_New_Mexico.jpg.
CC-SA.
(25) Gemstones come in many colors.. Public Domain.
(26) Mario Sarto,.http://commons.wikimedia.org/wiki/Image:Brillanten.jpg,http:
//commons.wikimedia.org/wiki/Image:Brillanten.jpg. GNU-FDL,CC-BY.
(27) http://www.flickr.com/photos/86624586@N00/10179314/in/set-252498/.
CC-BY.
(28) U.S. Department of the Interior, U.S. Geological Survey, J.D. Griggs. Lava is melted
rock that erupts onto Earth’s surface.. Public Domain.
(29) http://commons.wikimedia.org/wiki/Image:Druse.jpg. GNU-FDL.
(30) Rebecca Calhoun.. CC-BY-SA.
(31) John C. Nichols, USDA National Forest Service. Quartz veins formed in this rock..
Public Domain.
(32) [Taken by Rebecca Calhoun at 60X magnification on Intel Play microscope ].
CC-BY-SA.