488 Scientific Intelligence. 



part of 1913, but the last find of emeralds was made in August, 

 1912. Prospect work was renewed at the Ruby mine in Co wee 

 Valley, Macon County, N. C, and is being continued into 

 1914. The output of the gem minerals tourmaline, spodumene, 

 etc., in southern California was small, but some good gem mate- 

 rial was obtained. The exploitation of the less valuable native 

 semiprecious stones has continued with fair success, but the 

 increasing use of cheap, artificial products is making big inroads 

 on this industry." 



In regard to the diamond field in Arkansas it is stated that 

 "more active development was carried on in 1913 than in any 

 previous year. The nature of the work was not such as to defi- 

 nitely prove or disprove the value of the deposits, but it served 

 to show in what ways improvements could be made in the mills 

 and machinery so far used to treat the peridotite. The compa- 

 nies making the tests have not seen fit to announce the results of 

 their work, but they kindly allowed examination of their mines 

 and mills at the time of the writer's visit in July, 1913. Two 

 washing plants were built, one by the Ozark Diamond Mining 

 Corporation on their holdings at the northeast side of the original 

 peridotite area, and the other by the Kimberlite Diamond Mining 

 & Washing Co., on the west side of Prairie Creek. 



"The Ozark Co. operated its washing plant about three months 

 during 1913. Mr. Warren, the superintendent, estimated that 

 about 5,000 loads of 16 cubic feet of decomposed peridotite from 

 the original area and about 1,000 loads of gumbo and wash gravel 

 from the west foot of Twin Knobs were washed. The last of 

 this gumbo and gravel were being washed at the time of the 

 writer's visit, but no diamonds had been found in it. Several 

 hundred diamonds were recovered in washing the peridotite from 

 the original area. This peridotite was obtained from an open cut 

 300 feet long, 15 to 35 feet across, and 8 to 20 feet deep, with 

 tracks leading to the mill. A quantity of surface material was 

 washed in sluice boxes with riffles and yielded a larger per cent 

 of diamonds than the underlying peridotite. Most of the perido- 

 tite, even from the bottom of the open cut, was found to be so 

 decomposed as to be ready for washing as mined. 



" The Kimberlite Diamond Mining & Washing Co.'s plant is 

 nearly a mile from its lease holdings on the original peridotite 

 area The earth to be treated will be fed through a revolv- 

 ing screen and into a 10-foot diamond concentrating pan of 

 South African pattern. It is estimated that this pan will treat 

 from 100 to 150 loads of 16 cubic feet per day, reducing 100 tons 

 of earth down to about 1 ton of concentrates. The concentrates 

 will be further screened and then treated on jigs, and the final 

 concentrates examined on metal-covered tables in a well-lighted 

 room." 



The peridotites of Syracuse, N. Y., have also received atten- 

 tion, although no diamonds have been found thus far. It is 

 remarked that " The peridotites of Syracuse bear a marked 



