When I'm not exploring fresh caves or lands in minecraft, I'm busy trying to find deposits of diamond, gold and iron deep in the earth. So far I've just been digging around just above bedrock on a whim to look for these rare minerals but I've started thinking that I should be taking a more controlled, efficient approach to mining.

**What is the optimal mining strategy that yields the most rare minerals while minimizing blocks removed and time spent digging and traveling?**

**Edit:** The existing answers are great for mining, but no one has addressed travel time to and from the mine which is usually ~60 blocks downward and incredibly tedious. Solutions?
['https://gaming.stackexchange.com/questions/8310', 'https://gaming.stackexchange.com', 'https://gaming.stackexchange.com/users/1070/']
This a well covered question already but the technique I personally use isn't listed so I figure I'll add it to the mix. It isn't the technique for strip mining a chunk and extracting absolutely **everything** but it **does** expose lots of extra unseen blocks. 

It is much faster for quickly gaining things you want, it's incredibly easy to do, and is also less wearing on your pickaxes. 

***Getting down to and up from the mine:*** 

Use water held up by a sign at the bottom of a 1x1 shaft that is straight down starting up at the surface for dropping to diamond ore levels.  

To make it, dig a 1x3 section (so you don't mine beneath your feet) leave one side open for the drop shaft, fill the middle with cobble, and place ladders in the other shaft. 

The drop can be as great a distance as you want as long as the bottom of it looks like this: 

> 
> o = Stone  
> 
> **X** = Dug out  
> 
> **W** = Water  
> 
> **S** = A Wood Sign  
> 
> **L** = Ladder
> 
> 
> o **X** o **L** o  
> 
>  o **X** o **L** o  
> 
>  o **X** o **L** o  
> 
>  o **W** o **L** o  
> 
>  o **S** o **L** o  
> 
> **X X X L X** ( This is the mine )  
> 
> **X X X L X** 
> 
> 
> 

The drop is quick and completely safe. I use ladders for the return trip up but, if you prefer, (I think they take too long to make and are unreliable) you can make boat-waterfall ladder for coming back up. 

***Mining:*** 

1: Dig the standard 2x1 tunnels away from your entry point. I personally do this standing at Y: 9 so I occasionally run into unexplored caves but, if you are scared of cave mining, do it at Y:8 or Y:7. I don't suggest going to a lower depth than this because bedrock can get in the way, and ore veins that are beneath your feet will be smaller.

2: Every 4th block into your tunnel dig the upper blocks in a 1x1 shaft as far as you can reach on both sides of your tunnel. If you see an ore you like, dig the bottom out and go get it! 

The view of walls of your 2x1 tunnel would look like this

> 
> **x** = dug out  
> 
>  o = stone  
> 
>  o o o **x** o o o **x** o o o **x** o o o **x** o o o **x** o o o **x** o o  
> 
>  o o o o o o o o o o o o o o o o o o o o o o o o o o
> 
> 
> 

Extra optional step: 

3: If you want to squeeze more out of this type of mine, return once you have finished a good section and bring pieces of TnT. Place them in the back of the 1x1 shafts in the sides of your mine and set them off with Flint n Steel. I don't always do this because making TnT is a pain... but it does work.

**General Mining Tips:**

1: When mining always place torches on the right wall. When you want to come back just turn around and follow the torches that are now on your left. This is a very helpful technique for not getting lost in any mine exploring or digging.

2: If you have a well enchanted diamond shovel, dig out the sections of dirt you come across. High level shovels obliterate dirt at an insane speed and this typically reveals interesting stuff. 

Hope this helps!
i would like to add some (CREATIVITY) to the branch mining.

conventional branch mining is explained above. also in *seven sided die*'s answer there is mention that veins occur in **2x2 blocks**.

we generally think mining in term of 2d lets consider the third dimension.

[![made an illustration showing the method](https://i.stack.imgur.com/BYtoX.jpg)](https://i.stack.imgur.com/BYtoX.jpg)

(this is just an illustration) so the wool is to show that 4 spaces are left between corridors.

reason for leaving 4 spaces :-

* (Assuming that veins occur in **2x2 blocks**) the vein has possibility of appearing in center 2 block (out of 4 wool block i.e pink and blue wool in this figure) so it can be spotted while mining corridors on alternate floor (1st , 3rd , 5th, .....)
* same rule of possibility of spotting veins apply to corridor on (2nd , 4th , 6th, .....)
* the above shows the possible center block vein. block adjacent to cyan and maroon (in shown figure) can be easily seen so no doubt about that.

so this method reduces number of blocks mined and increases efficiency with respect to time.

**Key assumptions : veins appear in 2x2xX**(there is very very less probability of generating 1x1x1 vein ).