Built a field chest/trunk to hold all my Silver (I actually had 4 veins overlapping each other! Which made it hard to find since the wishbone puleses were constantly confused!)
Put a field chest with all my silver and built rockpiles with all the stone.
Logged on with my friends later to "lug it home" and the rock piles were still there, and silver and the chest was fully gone. 300 Silver lost.

100% certain it wasn't a friend theft.

Thinking a wolf/drake/golem may have smashed the chest while a friend was idled in base doing the upkeep chores. Whats the despawn timer of items?