| Onyx Cave | |
|---|---|
  | |
| Location | Santa Rita Mountains,Santa Cruz County, Arizona |
| Coordinates | 31°43′3″N110°46′9″W / 31.71750°N 110.76917°W /31.71750; -110.76917 |
| Length | 0.5 miles (1 km) |
| Geology | Permian limestone |
| Entrances | 1 |
| Access | Gated |
Onyx Cave is asolutional cave system with about 0.5 miles (0.8 km) of passages formed inPermianlimestone in theSanta Rita Mountains ofArizona.[1] It is part of theCoronado National Forest.[2] It was designated aNational Natural Landmark in 1974.[3]
The cave became a favorite spot to explore in the 1940s and 1950s. Vandals broke the formations and used paint on many walls to the point that the entrance was gated in 1962 in order to preserve it. Shortly afterwards the entrance was dynamited but was gated once again in 1974. Today access is controlled by Escabrosa Grotto, Inc.[4]