John T. Fuller’s last Stand, 1929-1931
In 1929, the ADC’s small plant had been modified slightly and some 1,500’ of six-inch water line installed for a renewed assault on the black surface layer. For sixteen months, the “sluicing” crew focused on a large unworked area north-to-northeast of the big plant, about one-third of the way up the big slope; and by November 30, 1930, the ADC and the DMEC together processed 3,500 loads and collected 2,559 diamonds (1,273.43 carats) for an average of 36.38 carats per 100 loads. This was the highest yield ever officially recorded for “surface” material. Again, the average size of diamonds recovered, one-half carat, indicates the finest screen used in that operation allowed a good many small diamonds to pass into tailings.
At the end of sluicing in November 30, 1930, Fuller or associates drew up the detailed “Statement of Operations” for the sixteen-month effort. Handwritten notations on the typed sheet estimated a minimum profit of $10,300 before deducting payments going into a trust fund for the lessor. This was hardly the handsome profits mentioned in his speech in 1928; still, it was unusual for the Arkansas diamond field.
John Fuller’s last report on the ADC’s property, in 1931, was an attempt to reconcile the lessons and the frustration of the past twenty-three years. In it, he first tried to set the record straight by explaining that the average yields he had used in previous reports were merely estimates made “for the purpose of illustrating the possibilities of the property and not the proved facts [Fuller’s underscoring].”
Then Fuller demonstrated his continuing struggle to balance promotional needs with professional restraint. Unquestionably, the beginning of the comprehensive report was good promotional literature. Fuller listed and interpreted tests made in 1907-1925 and came up with an average yield he had used as a model in the past, 13 carats per 100 loads of material (including both the surface layer and the underlying peridotite). Then he inflated that a bit by adding the exceptionally rich surface results of 1929-1930. Ironically, this final average, 14.2 carats, would, itself, be misused later by groups of promoters.
In the end, however, John Fuller remained basically the professional. Immediately after commenting on the 14.2 average, the report continued: “I do not, however, believe this average will hold as depth is gained but will only hold good for the first few feet where a natural process of concentration has taken place, thereby increasing the diamond content of the surface material.”
Having found little encouragement aside from the surface yield, Fuller concluded his final report by turning again to the comparative model he had used since 1908. “From all indications I would not look for a better average diamond content than the present-day average of the Jagersfontein Mine in South Africa, which is 7.19 carats per 100 loads.”
 “Statement of Operations at the Arkansas Diamond Mine for 16 months ending November 30, 1930,” in “Reports and Information, 41.
 Fuller’s comprehensive report on the ADC’s property in 1931 included the “surface” run in 1929-1930 (“Reports and Information,” 36); the results also appeared in the “Statement of Operations,” ibid., 41. The sources failed to break down the number of diamonds found before the DMEC’s lease and those recovered afterward, May-November 1930).
The composite mining map accompanying Fuller’s report of 1931 indicated the areas sluiced, with dates (“The Prairie Creek Peridotite Occurrence, Showing the Arkansas, Ozark and Mauney Mines with Surface Workings, Topography and Approximate Locations of Intrusive Rocks,” VI.A.3, “Maps, Blueprints,” Crater archive [originally misfiled in the “Misc.” box in the file-storage room at the Park Visitor Center, because of the map’s large size]). On the map, notice the favorable position of the water tower, which provided gravity-flow pressure for the hoses.
It is unclear which washing plant was used in this case. Lee Wagner and other local talent had built a small portable plant, placed on skids so that it could be moved around the field with a steam tractor (interviews of Alton Terrell, Murfreesboro), but the composite map showed it still sitting in an area sluiced in 1922-1925. The small plant Fuller built in 1909 was also available (it had been used again for sluicing operations in 1922-1925, after the big “mill” shut down). The “Statement of Operations” showed only $408.56 for “Reconstruction of Washing Plant.”
Photos in the Crater archive include many of Lee Wagner and the sluicing crew (VIII, File 23.85 is a good illustration).
Although the test produced the highest average yield ever described officially as coming from “surface” material, a much smaller test in 1910 reportedly averaged 36.9 carats per 100 tons (Fuller, “Arkansas Diamond Field in 1910,” 6). That clearly was surface material although it was not identified as such. In addition, field crews occasionally extracted even higher average yields when they ran across sand-and-gravel deposits in the field—in low wash areas; but those were abnormal super-concentrates, not regular surface mixture.
 “Statement” in “Reports and Information,” 41.
 “Estimate of Unit Value,” in “Reports and Information,” 36.
 Ibid., 37.
 Ibid. About two years later, John T. Fuller retired as chief engineer of the Aluminum Company of America. He died May 18, 1939, at age 59 (obituary, “John Torrey Fuller,” New York Times, May 19, 1939, p. 21).