Martin’s Diamond Corporation of America
Although the principals were informed soon after the test, the Bureau’s results were used primarily for government decision-making and were not publicized generally until December 1948. Meanwhile, Trust A discounted the results and kept trying to put together a dependable testing venture—the previous operations had stagnated. Finally, in May 1947, the Diamond Corporation of America (DCA) emerged, headed by a member of the Trust, Glenn L. Martin of Baltimore.
Martin’s DCA undertook a massive test of the entire pipe in October 1948-September 1949. The corporation built a large plant near the east edge of the volcanic breccia, immediately below the current park visitor center. For easier access to all parts of the the field, bulldozers filled the deep ancient gully running southward along the east edge of the big slope; and before the testing ended, the lower two-thirds of the slope, formerly torn up by pits and big trenches, had been leveled as evenly as a football field. In the process, heavy equipment buried tons of field debris and many streams of diamond-bearing gravel that had accumulated over the decades. The wide drainage cut on the west side of the southeast slope was also filled in.
The DCA’s random gathering of samples, with a large volume taken from pits on the west half of the pipe, inevitably drew criticism, as did apparent weaknesses at the processing plant. Yet, when it was all over, the results would hardly have surprised anyone familiar with the history of the pipe. The plant reportedly treated about 125,000 short tons of material and recovered 840 diamonds weighing 246 carats. Diluted by the high volume from the barren west side, the sampling yielded an average of almost 0.2 carat per hundred loads. As in previous tests, a great many tiny diamonds were allowed to pass through the smallest-mesh screens.
 In late 1945, the trustees awarded Allen B. Williams of St. Louis the right to form a mining company (Oil and Gas 7, 223, Mining Lease, Arthur and Schneberger to Williams, September 28, 1945). The trustees then cancelled the minerals lease to NADC (Misc. 7, 326, Cancellation, December 11, 1945). After no evident activity, Williams was forced to transfer his rights to the Diamond Corporation of America (DCA) in May 1947 (the assignment was stated later in Oil and Gas 7, 242, Termination of Lease to DCA, April 1, 1950; legal action was involved). Martin, President of the DCA, owned the Glenn L. Martin Company of Baltimore.
 The Crater archive has a fairly good photographic record of the process (VIII; on microfilm). Those photos have not been numbered for reference (the recent transfer of the archive to the new Crater of Diamonds Discovery Center  should solve this problem eventually.)
 Infra, “Recreational Mining.”
 The leading critic of the period was John Q. St. Clair, a mining geologist who became involved with the Arkansas diamond field in the mid 1940s. His critiques of the Bureau of Mines and the Martin operation were expressed primarily through an unpublished, but often cited “Report on the Arkansas Diamond Property,” August 14, 1956, pp. 6ff. (bound copy in V.B.10, Crater archive; copy in Parks and Tourism vertical files, “Crater of Diamonds”; on microfilm, roll 4). To some extent, St. Clair was influenced by George Vitt and the Millars. As well as anyone else, however, he represents the new wave of geologists who in the postwar era began misinterpreting John Fuller’s earlier statements while trying to build a case for renewed testing and mining (infra, “New Wave of Diamond Fever”).
 This loss of “fine-mesh” material especially concerned John St. Clair, who thought the Pike County pipe would be a good source of industrial-grade diamonds (ibid.). The outcome of the test was noted by St. Clair (8) and an assortment of publications. The US Bureau of Mines outlined the basics clearly: a total of 246.15 carats, valued at $984.60; a total of 840 diamonds, the largest 4.5 carats; about 90% small industrial crystals ranging from 0.10 to 1.0 carat; an average yield of 0.16 carat per 100 loads—16 cubic feet or 1,600 pounds each load (“Gem Stones,” Minerals Yearbook, 1949 [Washington, D.C.: US Department of Interior, Bureau of Mines, 1951], 546). St. Clair and some other sources used approximately 0.2 carats per 100 for the average. John Sinkankas’ popular guidebook repeated the BM’s statistics (Gemstones of North America, Vol. 3 of Gemstones of the World series [Princeton: D. Van Nostrand Co., 1959], 37).
Also see the Arkansas Gazette’s final report on the testing, reprinted as “Corporation Gives Up on Mining Arkansas Diamonds,” Pike County Courier, November 25, 1949, p. 1. “Arkansas’ dreams of a diamond empire may have been completely written off in a corporation dissolution filed in the secretary of State’s office yesterday,” it began. Corporate officials named in the dissolution were Glenn A. Martin, Baltimore; Ethel P. Wilkinson, Logansport, Indiana; Jan Porel, Baltimore; Roger P. Brennan, Shaker Heights, Ohio; and Joseph C. Little, Lyndhurst, Ohio. According to the State Geology Division, diamonds recovered in the test, 90% industrial, were valued at only $900 (at the current market price of $4 per carat for industrials).