[TerrorBite]

(good thing I decided to get a melee scroll the other day ^.^) yeh I noticed this too, however I didn't try mining without a pick axe (I've done enough of that before), but I did see a few others try it, mai goodness! They couldn't even seem to get the rock to crack!

[edit]I went back and tried myself, you have to hold down the s button first, then tap toward the rock with the direction key repeatedly while still holding down s. Although it is difficult to get positioned correctly :P [edit]