Shatter Cones

Sierra Madera Shatter Cone - 190g. 190 grams. Approximate size: 2.0" x 3.0" x 1.0". Location: Sierra Madera Crater, Pecos County, Texas. Well-defined striae on both sides and edges. Side one features radiating coarse-to-fine striae on a concave surface with blunted apex features; side two has moderate striae with at least two small apex features. This is a shatter cone specimen in Permian limestone from the Sierra Madera Crater in Pecos County, Texas. Shatter cones are rare impact-related structures with distinctive cone-shaped fractures and grooved, radiating striae that form under extreme shock pressure from hypervelocity meteorite impacts. The discovery of shatter cones, impact breccia, and shocked quartz in the 1960s helped confirm Sierra Madera as an impact structure. The crater formed about 100 million years ago and is an 8-10 mile-wide complex impact structure with a central uplift containing folded and faulted carbonate and siliciclastic rocks.