A different sound effect when hitting unstable or cracked rock

[rdnought]

Perhaps a bit more hollow of a rock mining sound, to serve as an alternate audible/tactileish warning to todays text tooltips that indicate the player should perhaps pause and rethink their next pickaxe swing.

Sincerely, A spelunker who definitely-did-not recently fall into a pit of locusts whom were all promptly buried in metric tons of granite.