Quick mining question

[MagicManICT]

So one of the X'es must be a cavein which makes the B's and C safe, but they weren't.

Did you consider this:

one explanation i can think of is that the first tile you mined (the cave wall) was detecting a cave-in tile on one of the three non-minable (cave floor) tiles,

[Sprymazi]

So one of the X'es must be a cavein which makes the B's and C safe, but they weren't.

Did you consider this:

one explanation i can think of is that the first tile you mined (the cave wall) was detecting a cave-in tile on one of the three non-minable (cave floor) tiles,

That must be it. But that in my opinion is a bug then if that's how it works

[MagicManICT]

It's only a faulty assumption. Nothing in the world says cave tiles are stable. You can just make a bad pick and cause a cave in on the very first tile you mine, too.

[MooCow]

To directly answer OPs question.

The amount of dust is equal to the number of adjacent cave-in tiles. Tiles are NOT adjacent to themselves.