Stones are minor minerals and unless you want to engage more than 20 persons, or dig below six meters from ground and use heavy machinery, the permission to start a stone crushing is granted by the district collector (or on his behalf by the Sub Divisional Officer ) on recommendation of the Tahsildar. The procedure (and definitions like what is heavy machinery) varies from state to state, and even from district to district.

Tahsildar (or the staff deputed by him) has to be satisfied that

The land from where you will take the stone belongs to you or is a government land available for stone mining.
The mining and crushing activities will not cause any public nuisance such as noise and/or dust problem for the local inhabitants or important roads like national high ways and major district roads.
The activities will not affect any water source.
So it is worth while to buy up the entire area before you apply to the Tahsildar for permission. Ownership of the land also helps as a collateral for bank finance. The support of the local villagers is a valuable asset for stone mining.

If every thing is in order the permission from (or on behalf of) the district authorities can be obtained within a month or two.

If the scale of mining and crushing is expected to increase beyond the scope of the District Collector’s office and the permission of the state government is needed then applications for it must be submitted well in advance (at least before two years) as it can be time taking in spite of regular follow up.

Tahsildar office is the right place to start inquiries about stone mining and crushing.