VELARDENITE FROM A NEW LOCALITY IN TULARE 

 COUNTY, CALIFORNIA. 



By Earl V. Shannon, 

 Assistant Cvrator, Department of Geology, United States National Museum. 



INTRODUCTION. 



Dr. Esper S. Larsen recently forwarded to this department for 

 accession and chemical investigation some specimens which had been 

 received at the United States Geological Survey from Tulare County, 

 California. (Cat. No. 94342, U.S.N.M.) These specimens, which 

 when received were labeled " uranium ore," were examined optically 

 by Doctor Larsen and found to be composed chiefly of a mineral of the 

 melilite group. This mineral has since been analyzed in the Museum 

 laboratory and proves to consist largely of the end member of the 

 melilite group named velardeiiite by Schaller, The California ma- 

 terial is very similar in composition to that from Velardeiia, Mexico, 

 upon which the species velardenite was instituted. 



PHYSICAL PROPERTIES AND ASSOCIATED MINERALS. 



In the hand specimen the material is coarse-granular and is dull 

 olive-green in color except near certain narrow veins about .3 mm. 

 in thickness which traverse the specimens. These veins are filled 

 with a white porcellanous material, on either side of which for a 

 space of about 5 mm. the color of the velardenite is pitch-black. An 

 occasional grain shows well-defined cleavage. The luster is greasy 

 to resinous. Under a lens the specimen is seen to be dotted with 

 small grains of garnet which have a yellow-green color, which dis- 

 tinguishes them from the duller green velardenite. 



In this section the velardeiiite makes up a fabric of coarse inter- 

 locking grains. It is colorless except near the narrow veinlets. The 

 latter are white and practically opaque under the microscope and 

 probably consist of cryptocrystalline silica. Near them the velar- 

 deiiite is thickly dusted with a very finely disseminated brownish- 

 black material. The larger grains of velardeiiite frequently show 

 a well-defined cleavage in one direction with a rather perfect parting 

 at right angles to the cleavage. Scattered throughout the section are 

 small irregular grains of isotropic yellow-green garnet. These occur 

 both as irregular tongue-like grains between the crystals of velar- 

 denite and as small inclusions in the crystals of velardeiiite. The 

 garnet grains inclosed in the velardeiiite crystals are in many in- 



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