You can even create your own by giving unopened geodes a sharp tap. The geode won't break but it will loosen up the inside crystals creating the "rattle rock".

Hi Roger, here's a pic of a cavity in a quartz crystal with loose pyrite crystals in fluid. There is a gas bubble in the cavity too and many of the pyrite crystals adhere to the bubble through surface tension. Invert the specimen and some of the pyrite crystals tumble slowly through the liquid to the bottom of the cavity. Hard to photograph because many of the visible pyrite crystals are embedded in the quartz just under the surface (not in cavities).

Not quite "rattling around'' but the closest thing I've got.

Tim

 Yes, we would love to know, please!

Cheers, Herwig

No worries, "nothing is broken"!  :-)

Tim, considering the mineralogical importance of this specimen: please submit the photo you added to this thread as a regular Mindat photo, and link it with the locality.

Then add the full description (you gave here) to the photo caption.

That way all members can find the photo if they do a search for it.

Thank you.

Cheers, Herwig