plutonic
adjective
plu·ton·ic plü-ˈtä-nik 
1
: formed by solidification of magma deep within the earth and crystalline throughout
plutonic rock
2
often capitalized : plutonian
Example Sentences
Recent Examples on the Web Simon O’Neill unleashed a gleaming, live-steel tenor, and Franz-Josef Selig’s plutonic bass made for an imposing Hunding. 
Globe Staff, BostonGlobe.com, 29 July 2019
Globe Staff, BostonGlobe.com, 29 July 2019 Word History
Etymology
Latin Pluton-, Pluto
First Known Use
1596, in the meaning defined at sense 2