Quartz

specimen number:
2292253

location:
Dryhead Agate Mine, Big Horn Co., Montana, USA

description:
Beautiful classic example of what is known as a dry head agate. Cut and polished on one side, very pretty.

The Dryhead agate locality, situated within the Bighorn Canyon area of Big Horn County in southeastern Montana, is a celebrated source of colorful, highly banded fortification agates. Geologically, these agates formed as secondary silica replacements within the dissolution cavities and limestone vugs of the Mississippian-age Madison Limestone formation. Silica-rich groundwater filtering through the sedimentary strata slowly deposited concentric microcrystalline chalcedony layers, with trace amounts of iron oxides imparting distinct bands of deep red, orange, yellow, brown, and white. Small-scale commercial surface quarrying and private hand-digging on claims in the remote Dryhead region began expanding in the 1940s and peaked during the mid-to-late twentieth century as the lapidary hobby grew in popularity. While the creation of the Bighorn Canyon National Recreation Area restricted access to portions of the original collecting grounds, limited seasonal extraction on remaining private claims and surrounding permitted land has continued to supply these uniquely patterned agates to collectors into the 2020s.

Questions about this specimen?
Send an email or call us: 314-341-1811.