Calcite, Quartz (Var: Chalcedony)
US highway 27 roadcut, Halls Gap, Lincoln County, Kentucky, USA
Calcite is common at Halls Gap. Crystals are negative rhombs which are often intergrown to the point of forming hemispherical masses. This geode is about 6 cm wide and is covered in a variety of quartz called chalcedony. Specimen is in the collection of, and photographed by, Alan Goldstein.
© Alan Goldstein