References

C. W. Chesterman, 1978 The Audubon Society's Field Guide to North American Rocks and Minerals, Alfred A. Knopf, Inc., 1979

Gaines, R. V; H. C. Skinner, E. E. Foord, B. Mason, A. Rosenzweig, 1997 Dana's New Mineralogy, John Wiley & Sons, 1819p.