Where is Steelix's Mega Stone?

Question

I can't find it I'm surprised no-one has asked it so where do I find it

Answer 1

The Steelixite is located in granite cave on B2F to the right of the big rock. If you see a sparkling thing it's the Steelixite. Note the Steelixite also requires a Mach Bike to get to.
Hope I helped!
Source1
Source2

Answer 2

Granite Cave

Should help

Hope this helps!