30 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60 



si|[!fned a new serial number, and the original number accompanying 

 the sand is given. It is to be remembered that none of these are 

 natural sands, all having been greatly concentrated by gravity proc- 

 esses or separated magnetically before coming to the museum. In 

 many instances the samples are merely fractional products of several 

 successive concentrating and purifying processes. The arrangement 

 is by localities, the counties being listed alphabetically. 



ADA COUNTY. 



1. Snake River, near Boise. Original number P 114. Abundant quartz ; rare 



obsidian, biotite, pyrope, augite, olivine, chalcedony, and hornblende. 

 Probably tailings from a concentrating table. Average grain diameter 

 0.5 mm. 



2. Same locality. Original number P 114. Abundant quartz; common augite 



and olivine ; rare biotite and obsidian. Evidently also tailings. Average 

 grain diameter 0.75 mm. 



3. Same locality. Original number P 114. Abundant quartz and ilmenite; 



rare pyrope, almandite, biotite, magnetite, olivine, augite, and obsidian. 

 Average grain diameter 0.5 mm. 



BINGHAM COUNTY. 



4. Snake River, at Rosa. "Auriferous sand." Cat. No. 53,625 U. S. N. M. 



Abundant ilmenite, magnetite, pyrope; occasional augite, almandite, and 



quartz ; rare zircon, gold, olivine, corundum. Average grain diameter 



0.1 mm. 



BOISE COUNTY. 



0. Centerville. " Monazite sand." No number. Abundant monazite, ilmenite, 

 quartz, and zircon; occasional almandite. Grain diameter 0.3-0.5 mm. 



6. Grimes Creek, Centerville. Original number P 249. Abundant quartz; 



common monazite, biotite, ilmenite ; rare almandite and zircon. Grain 

 size, average, 0.5 mm. 



7. Centerville. "Monazite separated by Lovett separator." Cat. No. 90,480 



U. S. N. M. Abundant monazite, zircon, ilmenite ; occasional magnetite and 

 quartz. Average grain diameter 0.50 to 0.75 mm. 



8. West side of Grimes Creek, i mile north of Centerville. Original number 



P 657a. Abundant quartz, kaolinized feldspar; rare rauscovite, alman- 

 dite, ilmenite, biotite, hornblende, and epidote. Average grain diameter 

 1 mm. Probably tailings. 



9. Centerville. Original number P 771 " oversize." Common polycrase, ilme- 



nite, samarskite; rare gold, uraninite (?), tapiolite (?), microllte (?), 

 pyrochlore (?), monazite, hematite, magnetite. Average grain size 5 mm. 



10. Oaks Placer Mine, Centerville. Original mark " P 670, ilmenite, 2.3 am- 



peres." A magnetic concentrate. Abundant biotite ; common monazite 

 and zircon ; rare epidote, quartz, limonite pseudomorphs after pyrite, 

 and almandite. Grain size average.? 1 mm. 



11. Centerville. Originally marked " monazite 5 amperes." Abundant mona- 



zite, with rare zircon, muscovite, biotite, and feldspar. Grain size 0.50 

 to 0.75 mm. 



12. Centerville. Original No. P 670. Marked "zircon, under tails, 20.2." 



Abundant zircon ; rare quartz, garnet, monazite. Grain size varying 

 from 0.10 to 2 mm. 



13. Idaho City dredge, Idaho City. Original No. P 654. Mainly monazite with 



common ilmenite and zircon. Grain size 0.10 mm. 



