The First Level Four Building [Ten Thousand Words-Please Vote]

Deep inside the mountain cave.

After deploying the Star-Spiral Cloud Barrier Formation, Ji Yuan took the huge rock he had found at the volcanic crater from his Storage Bag.

Thud—

The huge rock hit the ground with a dull thump.

Ji Yuan crouched and ran a hand over its black surface. It felt slightly warm.

"I wonder what's hidden inside."

Its exterior told Ji Yuan nothing, and his Divine Sense could detect nothing either. That left only one final method.

Frostfall flying sword, out!

At his command, the flying sword swept past in a streak of white light, shaving a layer off the rock.

Beneath the black stone was more black stone. He had cut away too little. Ji Yuan steeled himself, turned the flying sword into a three-foot blade, and slashed at a corner.

Clang—

The sword sank half a foot into the stone before it was thrown back.

"Hm?"

Ji Yuan's attention sharpened at once.

Frostfall was a Mid-Grade Spirit Artifact, yet even it had been repelled. Just how hard was whatever lay inside?

Now that he knew he could not damage its contents, Ji Yuan stopped worrying. He drove the sword through the rock again and again, cutting and sweeping until its outer shell fell away and revealed what was inside.

A stone within a stone.

The stone inside—or rather, the Immortal Material—was finally no longer black. It stood half as tall as a person, transparent on the outside, with molten fire flowing within. It was beautiful.

Even if he never used this ore to forge anything, it would make a splendid ornament in his Cave Abode.

...But this looked like Third Tier Fire Marrow Crystal!

That stuff fetched a hefty price. A piece this large had to be worth at least eight hundred, perhaps a thousand