You are right
…and my use of “plutonic” is either outdated or plainly wrong.
I found this for anyone who wants to read more :
https://en.m.wikipedia.org/wiki/Lava
“Properties of lava”

Because of the role of silica in determining viscosity and because many other properties of a lava (such as its temperature) are observed to correlate with silica content, silicate lavas are divided into four chemical types based on silica content:
felsic,
intermediate,
mafic, and
ultramafic.