What do we call molecules that are only
made of hydrogen and carbon?

Hydrocarbons

Hydrocarbons are organic molecules consisting entirely of carbon and hydrogen.

answer; the above answer to the above statement is (true)

phaneritic textures in which phaner means visible so phaneritic textures are standard of impertinent volcanic rocks. these rocks crystallized gradually under the surface of earth. when the magma cools deliberately then the ores have chance to develop and produce long crystals.