Following John Huddleston‘s lead, Reyburn’s workers had kept finding diamonds on the surface of the field. Huddleston, himself, accounted for at least half of the thirty-three collected by early March 1907. The total recovered, overwhelmingly from surface material, jumped to almost 250 in the spring of 1908 when a crew exposed a large number while clearing ground for the first plant. Then, with the plant operating, the count reached about 700 by the end of the year. The largest diamond weighed 6½ carats.
By the end of 1908, the “very incomplete records which were kept of a few washing operations” indicated an average yield of almost 21 carats per 100 loads of material (the standard tram load of the time was about 16 cubic feet, or 1,600 pounds). The reported average size of the diamonds, about one-half carat, meant that many small diamonds either were allowed to pass through the smallest-mesh washing screens or were otherwise lost. In either case, the loss came largely from a tough, frustrating surface material.
The diamonds were concentrated in a layer of rocky, humus-enriched “black gumbo” averaging about one foot thick and extending at places to four and one-half feet. They usually turned up after vegetation was disturbed and rains flushed the loose dirt from around them. Although the gumbo clay always proved difficult to process, diamonds still could be picked up by hand or be screened from the topsoil and drainage ditches in the field with even the most primitive equipment. “The number of diamonds recovered in this manner (on the surface accidentally or by search) forms a record[,] as no mine in South Africa has ever had such a surface showing, not even famous Kimberley,” said J. G. Woodford, the mining engineer hired in 1908 to direct Reyburn’s field operations. Even a turkey reportedly picked up two diamonds—tiny crystals the county sheriff said he found in its craw while dressing it.
 “More Options Taken,” January 16, 1907, p. 1; “Four More Diamonds,” March 9, 1907, p. 1. At that point, field work and washing at the Little Missouri River picked up; the overall count accelerated (“Fourteen Diamonds Found,” March 13, 1907, p. 1).
Sub-surface finds offered a sharp contrast. By the fall of 1907, only three diamonds had clearly been taken from the “green ground” below the dark surface layer.
 John Fuller reported “some 700” diamonds recovered in all mining and washing operations by the end of 1908, with 6½ carats the largest (Report to ADC, 26). George F. Kunz and Henry S. Washington, “Notes on the Forms of Arkansas Diamonds, American Journal of Science, 24 (1907), 275-276, said of about 140 diamonds found to date (by Aug. 12, 1907, the time of writing): “The largest diamond weighs 6y carats, and is . . . of an absolutely pure, pellucid white, free from inclusions. . . . Another stone weighs 6‚ carats, several about 5, 4, or 3, and from this they run down to 1/64 carat, the average being probably about one carat.” Kunz and Washington, “Diamonds in Arkansas,” Transactions of the American Institute of Mining Engineers, 39 , 173, repeated the statistics of their other writings in 1907).
Although the totals included diamonds found in the matrix below the distinctive surface layer, those were extremely few until the plant was built in mid-1908. Then more sub-surface finds occurred, but the yield remained far below that of the surface.
The bonanza found with the clearing of the first plant site in May-June 1908 impressed Fuller, and certainly helped him decide to remain in Arkansas (Fuller, Report to ADC, 25; also Fuller, Report to Loree, 13; Fuller, “Diamond Mine in Pike County, Arkansas,” EMJ, 87, No. 3 (January 16, 1909), 154.
 Fuller, Report to ADC, 27 (cf. the average yield for 1907-1908 that Fuller cited over twenty years later: “Estimate of Unit Value in Carats Per Load, 1931,” in “Reports and Information,” 36). Taken out of context, this paragraph of Fuller’s report to the ADC appears to say the property tested at 21 carats per 100 loads (0.21 per load), although that average depended largely upon surface diamonds.
 Fuller to ADC, 26, noted the average size, which was consistent with his report in 1931. In 1920, another authoritative source reported an overall average of “a little less than half a carat” (Reyburn and Zimmerman, “Diamonds in Arkansas,” 983).
Fuller’s public criticism of the ADC’s methods (“Diamond Mine in Pike County,” EMJ [January 16, 1909] 154), displayed impatience while neglecting to mention the role of surface material: the average yields reflected “haphazard experimental tests” with “inadequate washing machines, and the chances are that as many diamonds were lost in tailings as were recovered.” Twenty years later, Fuller repeated the criticism in a public speech: “. . . they put up a test plant and did considerable work on the property. The results were negative and in my opinion they were negative because the work was improperly done. . . . All of the money that has been spent on it, in my opinion, might just as well be thrown into the Arkansas River because results were not obtained in the right way” (“Public Statement By John T. Fuller on April 7, 1929” [sic.; actually 1928], in “Reports and Information,” 33).
As for losses during processing, however, competent mining companies did not ordinarily dispose of tailings haphazardly—especially when they suspected problems with processing, which was always the case with the black gumbo. Routinely, suspect tailings were kept for later reprocessing, a safeguard Fuller himself used (“Washing for Diamonds in Pike County,” Nashville News, December 10, 1910, p. 1: “Engineer Fuller, who is in charge of the work, states that only a portion of the stones are being found under the present method of working the dirt, and that it will all be worked over when the machinery is installed, and that he expects to find as many more as he has already secured, at the second working”). Similarly, runoff from grease tables usually was trapped in a holding pond. Even if tailings were rerun, however, most of the loss would have occurred again unless a company switched to a finer mesh for its smallest screens—which would have made it even more difficult to break down the black gumbo.
It is also worth noting that the sub-surface breccia processed more easily than the surface gumbo, which meant a lower rate of loss for the breccia.
 This was referred to also as “black ground.” Hugh D. Miser and Clarence S. Ross of the U.S Geological Survey included the description in the various editions of their report. Miser and Ross, “Diamond-Bearing Peridotite in Pike County,“ Contributions to Economic Geology, Part 1, U.S. Geological Survey Bulletin 735-I (1923), 295: “The soft earth at the surface is black from the presence of organic matter and is thus known as black ground. It is waxy like gumbo and is as much as 4 1/2 feet thick, though it is usually only about 1 foot thick. At places fully half of the black ground is composed of well-rounded pebbles of novaculite and angular fragments of sandstone and quartzite.”
Fuller said in an early report: “Overlying the greater part of the whole [35-acre] area to a depth which does not exceed 1 foot, is a black vegetable soil locally known as ‘gumbo.’ This soil contains some peridotite and a mixture of other rocks and soils brought in by the surface waters” (“Diamond Mine in Pike County, Arkansas” , 154).
Samuel W. Reyburn and Stanley H. Zimmerman, “Diamonds in Arkansas,” 984, said that about 75% of the “pipe” was covered by “sticky black residual clay derived from the underlying peridotite and vegetable matter and called ‘gumbo’ locally” and that large quantities of “water-worn pebbles and fragments of conglomerate derived from the Bingen sand” littered the gumbo. “The Bingen sand consists of intercalated beds of sand, clay, and gravel” (layers of material, with some mixing over time). The material had washed over the area as higher elevations immediately to the north weathered.
Rocks in the diamond-bearing peridotite also derived from near-surface deposits of sandstone and quartzite, which were shattered by the gaseous volcanic explosion that formed much of the pipe. Henry Washington, however, and later Reyburn and Zimmerman (ibid.), failed to notice the sub-surface inclusions, and therefore believed a typical magmatic flow had worked through the strata to form the pipe (Kunz and Washington, “Occurrence of Diamonds in Arkansas” , 1250; “Diamonds in Arkansas” , 170). Also see Edwin M. Williams, “Story of Ozark Diamond Mines in Pike County, Ark.,” Arkansas Democrat, October 26, 1912, p. 9, reflecting Washington’s influence (paragraph headed “Differences in Formation”). John Fuller, well-informed about diamond-bearing pipes, elected to avoid an argument with Washington (Fuller to ADC, in “Reports and Information,” 23), and thereby allowed Reyburn to continue believing his initial consultant’s erroneous conclusion.
 Woodford, Report (to Sam W. Reyburn, c. June 1908), reproduced in Fuller, “Reports and Information,” 17-18; Woodford, Report to the President, Ozark Diamond Mining Corporation, October 28, 1908, p. 4, “Misc.” box, Crater archive (in this later report Woodford retreated a bit: “The surface recovery of diamonds in such large numbers is unique. In my African experience I know of no mine there, except Kimberley, that can equal the record of this Arkansas Pipe”). Also Fuller, Report to Loree, 13: “. . . the surface finds in this way exceed anything that was ever discovered in the African mines at a corresponding period of their exploitation.” Cf. Fuller, Report to ADC, January 1, 1909, p. 25 (the surface finds “compare favorably with the finds of the African mines”), and Fuller, “Diamond Mine in Pike County, Arkansas” (January 16, 1909), 154 (“The number of diamonds found in this way is remarkable and is an indication of considerable wealth”). Whatever the exact expression, sources of the period agreed the surface concentration of diamonds was extraordinary.
Fuller described Woodford as “an old Kimberley diamond miner and a man of considerable mining experience all over the world” (Fuller to Loree, 16).
The black gumbo was normally hard to process in screens and wash tubs, where it tended to form clay balls. With simple hand equipment, it could be stirred and forced through even fine-mesh screens, especially if the soil contained considerable small gravel, which helped break down the clay; but the cylindrical screens and washers in plants clogged more easily. Critics of Reyburn’s slow operation tended to view this as a problem with management instead of material. A friend of Austin Millar, for instance, said at one point in December 1908, “Perhaps the trouble was with Supt. Woodford, however, rather than with their sticky, gummy rock” (Philip F. Schneider, geologist, to Austin Q. Millar, December 30, 1908, I.B, Crater archive).
 “Diamonds Plentiful,” Nashville News, January 9, 1907, p. 1.