page_title: Jackfork Sandstone
hierarchical_section_title: Jackfork Sandstone
caption_attribution_description: English: Quartz Locality: Jeffrey Quarry, Jeffrey, Pulaski County, Arkansas, USA (Locality at mindat.org) Size: small cabinet, 9.4 x 7.1 x 5.3 cm Quartz var. "Solution Quartz" So-called "solution quartz" from this quarry is supposed to be the best of its type. Solution growth of quartz here produced specimens of a unique brightness and surface sparkle, long prized. I think the moniker has to do with the fact the xls tend to be intergrown with many others in jackstraw groups which are not attached to matrix: The unlikely-looking floater status of these delicate groups thus reflects the fact they were in solution rather than deposited onto country rock. Today, mining of these specimens is done only by (risky) diving using scuba equipment, last I heard. I have not seen any good ones turn up fresh since the 1980s, as well. This specimen is a particularly rich cluster of solution quartz with a dominant crystal ending iin multifaceted terminations. It is mesmerizing, in its complexity at the micro level. And, it happens to be beautiful on a big scale, too! Complete all around, 360 degrees, this specimen is COVERED with crystals. Classic US material, hard to find... According to MinDat: A quarry located at Jeffrey near North Little Rock. Features 3 large, open cuts, now flooded. A rock quarry in Jackfork Sandstone. Started in the 1950's and operated through the 1960's. Reopened in the 1970's for specimens. Deutsch: Quarz Fundort: Jeffrey Quarry, Jeffrey, Pulaski County, Arkansas, Vereinigte Staaten (Fundort bei mindat.org) Größe: 9.4 x 7.1 x 5.3 cm
context_page_description: The Jackfork Sandstone, also referred to as the Jackfork Group, is a geologic formation associated with the Ouachita Fold and Thrust Belt exposed in western Arkansas and southeastern Oklahoma. It is named for Jackfork Mountain in Pittsburg and Pushmataha counties, Oklahoma.
  The Jackfork Sandstone is a thin- to massive-bedded, fine- to coarse-grained, brown, tan, or gray quartzitic sandstone with subordinate brown, silty sandstone and dark gray shale. It outcrops from Pulaski County, Arkansas in the east to Atoka County, Oklahoma in the west, a distance of over 200 miles. It is highly weather-resistant, resulting in a continuous chain of prominent ridges, including Rich Mountain, the second highest natural point in the Ouachita Mountains.
context_section_description: The Jackfork Sandstone, also referred to as the Jackfork Group, is a geologic formation associated with the Ouachita Fold and Thrust Belt exposed in western Arkansas and southeastern Oklahoma. It is named for Jackfork Mountain in Pittsburg and Pushmataha counties, Oklahoma.
  The Jackfork Sandstone is a thin- to massive-bedded, fine- to coarse-grained, brown, tan, or gray quartzitic sandstone with subordinate brown, silty sandstone and dark gray shale. It outcrops from Pulaski County, Arkansas in the east to Atoka County, Oklahoma in the west, a distance of over 200 miles. It is highly weather-resistant, resulting in a continuous chain of prominent ridges, including Rich Mountain, the second highest natural point in the Ouachita Mountains.
caption: Quartz from the Jackfork Sandstone
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