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Nally - Gibson Quarry, Georgetown, Central Kentucky Fluorspar District, Scott Co., Kentucky, USA

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Latitude & Longitude (WGS84): 38° 12' 24'' North , 84° 31' 32'' West
Latitude & Longitude (decimal): 38.20669,-84.52579

Primarily an underground mine, with small surface quarry. The Thomas vein, a series of calcite-barite-sphalerite veins cut through both surface and underground workings from the Middle Ordovician Tyrone into the Camp Nelson Limestones. It is located in the northern part of the Central Kentucky Fluorspar District, although the veins do not contain any fluorite.

This quarry is not accessible to most collectors, so don't bother contacting them. The owner will not let you in. They have been known to allow in university mineralogists for research purposes.

Mineral List

10 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

Middle Ordovician
458.4 - 470 Ma
Lexington Limestone

Age: Middle Ordovician (458.4 - 470 Ma)

Stratigraphic Name: Lexington Limestone

Comments: in west-central Kentucky, the thickness is 60-110 m; in north-central Kentucky the thickness is 15-60+ m; in northeastern Kentucky, the thickness is at least 45+ m; in east-central Kentucky, the thickness is 55-95 m; Middle Ordovician age

Lithology: Major:{limestone}, Minor:{shale}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Middle Ordovician
458.4 - 470 Ma
Lower part of Lexington Limestone

Age: Middle Ordovician (458.4 - 470 Ma)

Description: Limestone, argillaceous, medium- to light-gray, micrograined; in contorted bed with ball and pillow structure, and containing many chert nodules. Present in southeastern and central parts of quadrangle. In part of area, underlain by a few feet of medium-grained bioclastic limstone of the Tanglewood Limestone Member No. 1; elsewhere, underlain by irregularly bedded poorly sorted fossiliferous limestone of Grier Limestone Member. \nGRIER LIMESTONE MEMBER USGS Unit Info: GEOLEX (id: 1898) Limestone, medium-gray, fossiliferous, medium- to coarse-grained, bioclastic; in irregular beds about 0.5 foot thick, interbedded with fossiliferous micrograined to medium-grained bioclastic poorly sorted limestone in irregular to nodular beds; contains some sets 5 to 10 feet thick of medium-gray brachiopodal limestone with micrograined to fine-grained calcite matrix in irregular beds mostly 0.05 to 0.1 foot thick; irregular shale partings common between beds, particularly in intervals of brachiopodal limestone. Uppermost 15 feet of member grades eastward and northward into basal part of Tanglewood Limestone Member. Contains two thin zones of micrograined to cryptograined limestone with abundant silicified gastropods; upper zone, present in southwestern part of quadrangle, is about 80 feet below base of Millersburg Member and about 25 feet below base of Brannon Member. Lower zone, present in northern and eastern part of quadrangle, is 90 to 95 feet below base of Millersburg Member. Fossils are Rafinesquina sp. (collections E, F, G, and H), Zygospira sp. (collections G and H), Hebertella frankfortensis Foerste (collection H), Heterorthina sp. (collections H and I), Rhynchotrema increbescens (Hall) (collection H), Ambonychia sp. (collections G and H), an indeterminate modiomorphid (collections F, G, and H). Modiolodon sp. (collection G) ?Pterinea, two species of Ctenodonta belonging to the Ctenodonta levata group (collection G), Ctenodonta sp. (collections G and I), Cyrtolites retrorsus Ulrich in Ulrich and Scofield (collection G), Carinaropsis cymbula Hall (collection G), Loxoplocus (Lophospira) medialis burginensis (Ulrich in Ulrich and Scofield) (collections G and H), "Microceras"sp. indet. (collection I), "Cyclora"sp. indet. (collection I) and Heterotrypa sp. (collection E). \nEconomic (limestone): The Grier Limestone Member of the Lexington Limestone is quarried near Georgetown for road metal and concrete aggregate. The thinner-bedded, more argillaceous parts are discarded. Many small abandoned quarries are present throughout the quadrangle in both the Grier and Tanglewood Limestone Members. The limestone was used locally for building stone and road metal.

Comments: Ollr; Georgetown Quadrangle (GQ-605) | | Map description and column:

Lithology: Limestone | argillaceous

Reference: KGS Databases, Maps, and Publications. Kentucky 1:24,000 Geologic Map. Kentucky Geological Survey. [22]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

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