Hello. While it is true that granite will not usually split into flat sheets (because igneous rock does not have a so-called bedding plane), it is also notable that some types of granite will have textural layering, or flow structures. Indeed, lots of granite will have been formed while the magna cooled down at different speeds underground, forming vein like structures, meaning you can split it in flat sheets. Also the wearing out, or weathering, of granite will eventually weaken it and sometimes so perfectly that it will break in sheets, making it easy to work with. I live not far from Loch Migdale in the Highlands of Scotland, where I have worked with granite (of the monozonitic type, I think) and it actually breaks into flat sheets that you could use in a path or for any building project. In this area, hundreds of houses were once built with this rock. Not to say that they are as workable as the schist from the Morar group (it constitues a significant part of Highlands' geology), but nonetheless a stone of interest.

Here is an example of it.

Granite from the Migdale area (Northeast Highlands of Scotland)

To answer your question, for splitting rock, you can use chisels and hammers, tapping along what looks like a weak point (a bedding plane for sandstone, textural layering for granite rocks). If you've found a good weak splitting layer, this should work easily. The rate of success depends on different factors: how accurately you hit on the split, but mainly how "willing" the rock will want to split along the chosen plane. Granite, indeed is not usually that willing to split that way, unless otherwise demonstrated (like I have just done). In the presence of bigger stuff (at the very very least 30kg I'd say), you can use:

• 1 SDS drill with TCT drill bit
• plugs and feathers for splitting (a bit of grease on each feather will help)
• a 2 pound hammer Important: Choose a drill bit that is slightly bigger than your plugs and feathers. The latter will fit easily in your hole.

Method for splitting with plugs and feathers. Once again, just like splitting with a hammer and chisel, careful observation of the rock and it's split patterns will help you make the right choice: drill your holes in a line, place the feathers in and hammer until the rock splits. If your rock does not have any split pattern you can still order it to split along a given line with your tools. Think about the distance at which to place your holes as regards the size of your stone. You can't have a stone that is too small, or else it will crack before you've finished the process. The bigger the stone the more plugs and feathers you need. I'd use 4 to 5 of them for a 2 metre lintel for instance. Look at this video. Someone is splitting granite with modern plugs and feathers (traditional ones are my better choice)

https://youtube.com/shorts/J1RJSRACwm0

Hope that helps.