Roncari Quarry (Tilcon Quarry), East Granby, Hartford Co., Connecticut, USA
|Latitude & Longitude (WGS84):||41° 56' 16'' North , 72° 44' 22'' West|
|Latitude & Longitude (decimal):||41.93778,-72.73944|
|Köppen climate type:||Dfa : Hot-summer humid continental climate|
Quarry in the Jurassic (205 mya) Holyoke Basalt. Mineralization occurs in gas vesicles (pockets) and in fault zones, some of them heavily brecciated and recemented with fine-grained calcite.
Mindat Articles"Barf" Datolite by Paul Gilmore
20 valid minerals. 2 erroneous literature entries.
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 Macrostrat.org
174.1 - 201.3 Ma
Age: Early Jurassic (174.1 - 201.3 Ma)
Stratigraphic Name: Holyoke Basalt
Description: Greenish-gray to black (weathers bright orange to brown), fine- to coarse-grained, grading from basalt near contacts to gabbro in the interior, composed of pyroxene and plagioclase with accessory opaques and locally olivine or devitrified glass.
Comments: Part of Central Lowlands; Newark Terrane - Hartford and Pomperaug Mesozoic Basins. Part of Newark Supergroup (Upper Triassic and Lower Jurassic). Part of Meriden Formation of Krynine (1950) (Lower Jurassic); CT005.
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. 
Ryerson, Kathleen, H. (1972): Rock Hound's Guide to Connecticut. Pequot Press.
Hubert, John F., Paul E. Feshbach-Meriney and Michael A. Smith. (1992). The Triassic-Jurassic Hartford Rift Basin, Connecticut and Massachusetts: Evolution, Sandstone Diagenesis, and Hydrocarbon History. AAPG Bulletin: 76(11).
Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 398.