What is the benefit of ores obtained from silk touch?
- You can store ores before you get Fortune enchantment, then place the ores and get higher yields than before without Fortune
- You can store EXP this way (for example in coal) - just get the EXP later when needed by placing ores and breaking them
- Ore Fortune breaking at home is safe, you do not need to carry your expensive Fortune III pickaxe around lava in mines. Just get the ore home, place at floor and break it safely without losing materials or pickaxe.
- Ores use smaller amount of inventory space compared to ingots/chunks of material, especially Lapis (you can fill one inventory space just with like 4 lapis ores broken by fortune III, so having ores you can carry like 16x more)
- IF you use mods, the ones like GregTech or IndustrialCraft offer another way of ore processing, possibly getting multiple products (or byproducts) from one ore (macerator, ore refining etc, ore duplication process in general)
- Decoration
- Combinations of aforementioned methods
Be aware that some of those practics do not work on some servers, where placing of those ores is banned. Then some of the mentioned methods are not valid. However every Good and normal server has this not blocked. (as of in new versions the duplication bugs are hopefully resolved)
Antoine Hejlík's answer covers most of the benefits, but there's a few extra ones;
- There's several blocks that can mainly only be obtained through Silk Touch
Ores, mycelium & grass for spreading purposes, and Ice Blocks
The other answers (and comments) seem to be forgetting about the dear Ice Blocks, even though they have several uses!
- Can be used to create a variety of traps
- Can be used to to amplify the Soul Sand slow (Place an Ice Block directly beneath Soul Sand)
- Can be melted on demand to create water (and moved around beforehand) replacing a piston/water setup, and giving 'some' freedom.
- Can create 'speed' tunnels. Running and jumping on ice in a 2block tall tunnel is faster than running!
All thanks to silk touch :)
I haven't played Minecraft in a while, so there may be other uses now!
the main use of silk touch is for mining solid stone as opposed to cobblestone.
Silk touch mines the initial object in place of the item it drops (cant remember all the objects it affects though)
But say you were building a stonebrick castle, a silk touch pickaxe would mean you would not need to refine the cobblestone, as silk touch picks would directly mine smoothstone for you.
this means you can create the stonebricks faster and without using as much coal.
Theres probably more to it that ive missed but thats the key point, use your silk touch to mine objects that would normally drop other items, to get the original object. (Perhaps glowstone for example - give that a try and you may get a solid block in place of dust, but dont quote me on that one as ive not done this in a looong time.)
EDIT/tl;dr - When using silk touch for mining, its typically used either for transporting blocks like grass that arent otherwise easy to access, to obtain blocks like glowstone or stone brick more resource efficiently or to mine ores directly for decorating purposes. Another possible use would be, as mentioned by @Robotnik below, would be to try and move ores to locations that are easier or safer to mine with other pickaxes with other enchantments. Taking a redstone ore block up uses less inventory space than 5 - 10 redstone dust, meaning you can move it up more efficiently to mine again later with a higher droprate pick, or just to save inventory space when mining.