The Bonney Mine: A Rich Claim in Grant County Mining

A newspaper report from Lordsburg, New Mexico, dated December 24, 1915, declared that “the Bonney mine is the richest in the local districts” ^[1]. The report provided a detailed breakdown of the ore’s composition: the average values included approximately $4.50 per ton in gold, $4.00 per ton in silver, and $12.50 per ton in copper ^[1]. These figures were not merely hypothetical; the vein had already yielded assays as high as $80 and $100 per ton in many places, underscoring the mine’s exceptional grade ^[1].

As early as the 1880s, the Silver City Mining and Milling Company had developed properties in the Silver Flat district, including the “Old Timer” and “Volcano” claims, where three parallel veins cropped out for 1,500 feet across the surface ^[6]. These mines, located about half a mile southwest of Silver City, were described as containing “three distinct veins, possessing in their strike a remarkable degree of parallelism” ^[6]. By 1882, the company had sunk multiple shafts on the “Old Timer,” the principal working shaft reaching 210 feet, and a level extending 230 feet northward from the bottom of a 90-foot shaft ^[5]. Ore values from these properties ranged from $40 to $70 per ton in gold and silver, and the company’s engineer estimated the average mill recovery at fully $40 per ton ^[7]. The “Cosette” mine, regarded as one of the most valuable in the Territory, was considered part of the same series of deposits as the adjacent “Campbellite” ^[2][4].

The Silver City Mining and Milling Company had constructed a fifteen-stamp mill with a complete assay outfit and substantial buildings, at a cost of approximately $75,000, including the acquisition of an ample water right ^[3]. The mill was situated between one-half and three-fourths of a mile from the mines, connected by a wagon road in excellent condition for heavy quartz hauling ^[7]. The engineer noted that the entire cost of mill and water right approximated $75,000, and that the property was capable of supporting a doubling of mill capacity to thirty stamps ^[3].

The geological formations—described in 1882 as the “exact counterpart of the formation carrying the great deposits of Nevada and Arizona”—allowed for chloride ores with gold and silver content that increased with depth ^[4]. The same report noted that the ores were “perfectly free, the silver occurring in the form of chloride, and such of the gold as is visible to the eye bright and clean” ^[7].

Its average value of $20 per ton—and local peaks of $80 and $100 per ton—placed it among the most profitable claims in the area ^[1]. The mention of copper values echoes the contemporaneous copper boom at Clifton-Morenci, also noted in the same newspaper issue ^[1].

Though the Bonney Mine’s identity as “the richest in the local districts” was proclaimed only in that single newspaper report, its recorded ore values remain a concrete measure of the high-grade deposits that once defined the region’s mineral landscape ^[1].