The Dragon Graveyard

Even dragons know better than to hold on to Graveyard opal.

— Proverb

Geography

The Dragon Graveyard stretches out like a festering wound in the landscape. The surface is a sickly purplish-gray in color, with the appearance of stratified rock, but unlike shale or limestone, it resists any effort to break it up by mortal hand. Yet cracks run across the stone, up to a foot wide and too deep to see the bottom; what made these cracks is anyone's guess, but it's generally accepted as fact that it was nothing you'd want to run into on your way home. When rain falls, or water is spilled, it will run into the cracks as anywhere else, but they have never been observed to fill up with water. Instead, a pale fog forms inside the cracks, slowly rising towards the surface. When the rain is especially heavy, the fog will overflow, wafting across the landscape until it dissipates at the edges of the strange place.
Scattered across the land, embedded in the stone, are what appears to be humonguous, partially silicified bones, which gave the place its name. The surface of these is white and weathered, as might be expected from bones exposed to the elements for as long as they must have been there, but contain patches of smooth, pale opal, as though the precious stone ate the bone up from the inside. No skulls can be found among them; most of the bones (if that's what they are) are vertebrae, ribs, or what appears to be knuckle bones. Not all of them are to the same scale, either. While they all have in common that they're larger than most known living things, some pass that mark by a narrow margin while others make those bones look small by comparison.

Fauna & Flora

The only thing even suggesting life in the Dragon Graveyard are the giant bones, assumed to be the remnants of some great creature of the past. Not even moss or lichen will spread onto its stony surface, and there are accounts of hunted deer turning around on their heels towards their pursuer rather than try to escape across the barren land. Draft or riding animals tend to balk at the edges of the Graveyard, too, and only the most skilled horseman could hope to ride across - a feat that would likely take at least as long as just riding around it, and leave their horse foaming with sweat.

Natural Resources

Unlike the seemingly indestructible substrate, the bone and opal of the Dragon Graveyard can be damaged by mundane tools. Some of the bones closest to the edges of the area are pitted where fortune-seekers carved out sections of opal, hoping to make some quick gold. While it is indesputably fine opal, it also comes laden with all the superstition - founded or otherwise - about the place, and tends to change hands often as ill fortune gets blamed on the aquisition of the stones.