148g Koch Shaft MO Greisen Zinnwaldite Quartz Specimen KeepsCache For Sale

Weighing 148 grams and measuring 2.185\" x 2.25\" x .875\", this specimen from the Koch Shaft is a fantastic example of the high-temperature hydrothermal alteration native to the district. This piece acts as a geological window, offering a sharp contrast between a smoothly surfaced display face and a completely raw, natural reverse side.

​Close inspection reveals the distinct structural characteristics of the localized deposit:

• ​Contrasting Faces: The smooth front face exposes the dense, granular internal structure of the altered host rock, while the unpolished back remains rugged and highly textural.

• ​Zinnwaldite Mica: The raw, unpolished side hosts visible, dark micaceous clusters of zinnwaldite, a rare lithium-bearing mica that is a classic hallmark of the mine\'s unique greisenization.

• ​Heavy Greisen Matrix: A classic quartz-rich host displaying a tightly packed, sugary texture with greenish localized alteration.

• ​Metallic Disseminations: Small, dark, metallic ore flecks are suspended directly within the crystalline matrix.

• ​Natural Oxidation: Brilliant reddish-orange and amber iron oxide staining permeates the matrix, detailing the natural weathering of the metallic sulfides over time.

​Dimensions: 2.185\" x 2.25\" x 0.875\"

Weight: 148 grams

Locality: Koch Shaft (Einstein Silver Mine District), Madison County, Missouri

Provenance: Ex. Cox Family Collection

​The History

Originating from the historic Cox Family Collection, this greisen specimen is a superb representation of Missouri\'s only notable silver mining district. The Einstein Mine area is renowned for its rare high-temperature hydrothermal veins, and pieces that clearly display rare zinnwaldite mica clusters against a classic greisen matrix are highly sought after by regional dir=\"ltr\" style=\"margin-top:0; margin-bottom:0;\">​Koch Shaft Missouri, Zinnwaldite mica, Cox Collection mineral, Einstein Silver Mine district, Madison County MO geology, heavy greisen specimen, lithium mica, KeepsCache lapidary, hydrothermal vein, Missouri rockhound.