Well rock collector is a good term but if you make it your profession to collect and study rocks you are called a petrologist. A Rockhound.
A geologist is a person who studies rocks and rock formations. A rock collector or a rock hound is a person who collects rocks for fun.
Magma. Magma rises towards the surface when it's less dense than rock around it. Otherwise, it collects in magma chambers and cools, forming igneous rock.
A person that collects stones is called a rock collector or rock hound. A lapidarist is an expert on precious stones and the cutting and engraving of them.
It is an aquifer.
Rockhound. Those who study this professionally are called petrologists.
If you mean name given to molten rock then the answer is magma
The area underground where rainwater collects in the spaces between rock particles is called the "zone of saturation" or the "water table." This is where groundwater accumulates and flows through the pores and spaces in the rock or sediment.
Magma collects in a chamber beneath a volcano.
magma chamber
"The Rock" was the name given to the prison island of Alcatraz in San Francisco bay. It is also used as a name for Gibraltar.
I call myself a rock-hound when checking the shapes, patterns of lines and cracks, and different types of rocks compressed together on Manitoulin Islands North West shoreline. Glacial movement of years gone by created very unique and different sized stones and boulders here. Its a rock-hounds picnic area.
Zimeus