A nodule of stone having a cavity lined with mineral or crystal matter on the inside wall
Hollow mineral body found in limestones and some shales, commonly a slightly flattened globe 1-12 in. (2.5-30 cm) in diameter and containing a chalcedony layer surrounding an inner lining of crystals. The hollow interior often is nearly filled with inward-projecting crystals, new layers growing on top of old. The crystals are often of quartz but sometimes of other minerals
(mineralogy) a hollow rock or nodule with the cavity usually lined with crystals
Roughly spherical, hollow or partially hollow accumulation of mineral matter A few centimeters to nearly 0 5 m in diameter Outer layer of chalcedony lined with crystals that project toward the hollow center Crystals, often perfectly formed, usually quartz although calcite and dolomite and - more rarely - other minerals Most commonly occur in limestone, and less often in shale
A rounded irregularly shaped mass of stone having a cavity lined with crystals or mineral matter