In geology|lang=en terms the difference between igneous and tephrite
is that igneous is (geology) resulting from, or produced by, the action of great heat; with rocks, it could also mean formed from lava/magma; as, granite and basalt are igneous rocks while tephrite is (geology) an igneous rock consisting essentially of plagioclase and either leucite or nephelite, or both.
As an adjective igneous
is pertaining to, having the nature of fire; containing fire; resembling fire; as, an igneous appearance.
As a noun tephrite is
(geology) an igneous rock consisting essentially of plagioclase and either leucite or nephelite, or both.
igneous
English
Adjective
(
en adjective)
Pertaining to, having the nature of fire; containing fire; resembling fire; as, an igneous appearance
(geology) Resulting from, or produced by, the action of great heat; with rocks, it could also mean formed from lava/magma; as, granite and basalt are igneous rocks
tephrite
English
Noun
(geology) An igneous rock consisting essentially of plagioclase and either leucite or nephelite, or both.
(
Webster 1913)