It seems reasonable to assume that many places where there is easily accessible volcanic rock are also places where geothermal is possible, but the connection b

It seems reasonable to assume that many places where there is easily accessible volcanic rock are also places where geothermal is possible, but the connection between rocks like basalt and volcanoes can be more temporally distant that you may be thinking. If I go to a beach in the US Pacific North West, I can pick up basalt rocks/boulders/pebbles, but they last were in contact with an active volcano millions of years ago (approx 12mya is the usual number given locally, if memory serves)