In all technicality, the most common block in minecraft is Air. In terms of solid blocks, it's stone. There might be a few dirt blocks in the way, but digging around mostly yields stone.
The hardest block in Minecraft is bedrock. It is completely unbreakable unless on creative mode.
Underground
Minecraft is a block related game. The developers never intended for their to be circles in minecraft.
spawn it in
There are single player mods that enable this as a command. But most are for multiplayer if you are searching the plugin: WorldEdit is the most chosen
The most common creature in minecraft are cows, pig, chickens and shepp. But it also depends on the seed
right now in 1.5.2 there are 3 heres the a list .block of redstone .block of quartz .dropper
Apart from water and air, stone is the most common block, below the topmost dirt layer. Just dig, you'll hit some.
In Minecraft, the gold block is data value 41.
What is the strongest block in minecraft
A minecraft block is 1 Meter to scale in real life.
The hardest block in Minecraft is bedrock. It is completely unbreakable unless on creative mode.
There is no command block in minecraft. If you go to the Minecraft WiKi it will have all the information you need for anything in the game.
Underground
Minecraft is a block related game. The developers never intended for their to be circles in minecraft.
spawn it in
There are single player mods that enable this as a command. But most are for multiplayer if you are searching the plugin: WorldEdit is the most chosen