Shale gas is different – it too is a natural gas, but it is trapped inside rocks that have to be broken open ("fractured" or "fracked") to release the gas.
Kildagaas on erinev – see on küll ka maagaas, kuid paikneb kivimis, nii et selle kättesaamiseks tuleb kivim purustada (frakkida), et gaasi vabastada.