Smithsonite replacing Dolomite

specimen number:
2063264

location:
Philadelphia Mine, Rush, Marion Co., Arkansas, USA

description:
Classic specimen from Arkansas, the top of this matrix is attractively covered with rhombohedral crystals of what were once dolomite measuring to 1.3 cm in size. These crystals are now replaced by dark yellow sparkling crystallized smithsonite. In good condition for one of these, the color is very nice. The specimen comes with two previous collection labels, one from Ray DeMark and one from Al and Betty Tlush.

Located in the Rush Creek Mining District of Marion County, Arkansas, the historic Philadelphia Mine operated during the late nineteenth and early twentieth centuries, extracting valuable zinc deposits hosted within Paleozoic carbonate rocks. The locality became world-famous among collectors for producing exceptional zinc replacement specimens, particularly pseudomorphs of smithsonite after sharp rhombohedral dolomite crystals. Miners in the Ozark region colloquially nicknamed this distinctive bright yellow-to-orange smithsonite turkey fat, a name inspired by its resemblance to yellow poultry fat. The signature yellow coloration in these smithsonite specimens is caused by tiny trace inclusions of cadmium sulfide, known as greenockite. Today, the Philadelphia Mine site sits within the protected grounds of the Buffalo National River, making classic specimens from this historic locality highly prized and sought-after by collectors.

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