This is one of the rarest of calcite crystals, and outside of the Wind Cave area, is found in a handful of places around the world.

Dad stopped by a farm on the western edge of Wind Cave, and we began to explore.  We found a small cave opening, and directly in front was this stone.

We left this farm, and within the next hour lost our tent poles on the way to the Badlands.

These were found in the grasslands during our first rock collecting expedition. 

If you notice the "B", this was placed on this rock 35-40 years ago.   Why?

Well, these rocks were in our black light room, and when placed under the ultraviolet light, they either radiated an orange or green color.