248 A Book of Precious Stones
ings
where the members read papers and in many ways contribute information,
and which make field study trips to localities known to be productive
of specimens of interest. All who visit the collections at the American
Museum of Natural History should obtain Guide Leaflet No. 4 for the Collection of Minerals (which is a supplement to the American Museum Journal), written
by Louis P. Gratacap, A.M., Curator, Department of Mineralogy, of the
museum. For more extensive information applicable to this collection
and institution, and to similar ones, a most profitable investment
would b^the book by the same author, A Vade Mecum Guide to Mineral Collections, with a Chapter on the Development of Mineralogy, with
enlightening halftone illustrations and over two hundred figures of
crystals. There are also periodical publications devoted entirely or
in part to mineralogy. The growth of the mineral collection of the
American Museum of Natural History has been gradual, beginning with the
Bailey collection, which served as an introductory and fairly
representative series of specimens. A valuable accession was the most
remarkable group of specimens of malachite and azurite donated by the
Copper Queen Consolidated Mining Company of Ari-
