Turner — Unusual Minerals from the Pacific States. 343 



Art. XX LX. — Notes on Unusual Minerals from the Pacific 

 States ; by H. W. Turner. 



Mineral Phosphates. 



Pyromorphite. — This lead phosphate is found abundantly 

 in the Rocky Mountains and elsewhere, but, so far as known, 

 has not yet been reported from the Pacific slope. Mr. Gr. W. 

 Kimble, of Placerville, California, sent some specimens of 

 quartz from a vein in Mosquito Gulch, about six miles north- 

 east of Placerville. This quartz contains a little galena, and a 

 yellow-green mineral supposed by Mr. Kimble to be pyro- 

 morphite. The yellow-green mineral was tested by Dr. 

 Hillebrand and found to be pyromorphite. It occurs as color- 

 ing matter in botryoidal chalcedonic quartz, coating seams and 

 lining cavities ; and also as little crystals along seams in the 

 quartz. Mr. Kimble states that the vein occurs in gneissic 

 rock near granodiorite, and that it contains, besides the pyro- 

 morphite and galena, a little pyrite and gold. 



Monazite. — This phosphate of the cerium metals occurs 

 usually in granites and gneisses, notably in North Carolina* 

 and Brazil,f but is known to be common in many parts of the 

 world in sands. Mr. Waldemar Lindgren reports monazite in 

 abundance in the Idaho Basin, twenty-five miles NNE. of 

 Boise City. It is usually called "yellow sand." The monazite 

 occurs in small grains, and is presumed to have come from the 

 surrounding granite. Its occurrence here in considerable 

 quantity is of interest, as later it may serve as a source for the 

 rare earths of the cerium group used in the manufacture of 

 the mantles of Welsbach and other similar burners. North 

 Carolina and Brazil now furnish the commercial monazite in 

 sufficient quantity for this purpose. 



Apatite. — As is well known, apatite is a very abundant con- 

 stituent of many granodiorites and other igneous rocks, in the 

 form of minute grains and prisms. The composition of this 

 apatite probably varies, but to determine its character in a spe- 

 cific instance a gneiss was selected (No. 1743 Sierra Nevada 

 collection) which contains a relatively large amount of this 

 mineral. This gneiss was collected in the canyon of the North 

 Fork of the Mokelumne River east of the mouth of Bear River. 

 It is one of a series of old gneisses possibly Archean^: in age. 



*H. B. C. Nitze, 16th Ann. Rept. U. S. G-. S., pp. 667-693. This article 

 gives a complete description of monazite as to its chemical composition, 

 crystallographic character, distribution, production and bibliography. 



f O. A. Derby, this Journal, vol. vii, 1899, p. 343. Mining and Scien- 

 tific Press, Aug"! 21, 1897. 



$K. W. Turner, 17th Ann. Rep. U. S. Geol. Survey, Part I, 1896, p. 700. 



