Home   AmMin   GMR   RiMG   Collectors Corner   Directory   Short Courses 

Volume 3, page 192, 1918

Washington, D. C.

     Some months ago there was received at the National Museum for identification a peculiar rock, evidently a somewhat altered volcanic breccia, so injected with a blue coloring matter as to suggest lapis-lazuli. The manner in which the coloring matter was distributed, a portion of it in the cementing material and a portion actually replacing the original rock fragments, suggested its secondary origin and invited careful tests to ascertain its true nature. Thin sections under the microscope showed the coloring matter to occur as minute scales without crystal form and very irregularly distributed. These had the refractive indices and gave the chemical reactions of lazulite, which is a hydrous phosphate of aluminum, iron and magnesium. It is an interesting occurrence since it closely simulates, as above noted, lapis lazuli (lazurite), which has, however, a quite different composition.
     The specimen was received from Mr. Frederick L. Whitehead, of Hassel, Montana, who reports that he has found the material, thus far, only as float.

Footer for links and copyright

Copyright © 1918 - 2004 Mineralogical Society of America. All rights reserved