I’m assuming Tumblr’s sending out chatty Ask messages these days, but on the off chance some of you guys are actually interested:
it depends on the star! Younger ones like Sol (our sun) contain larger amounts of metals than older ones, as throughout the aging of the universe, elements have combined from an initial content of mainly hydrogen/helium down through progressively heavier elements. The oldest stars in the universe are primarily hydrogen/helium.
One of the ways astronomers date stars is through spectral analysis. Because different elements burn in different bands of the spectrum, you can get a sense of what a star is made of by breaking down the contents of the light it gives off—and thus you can get a sense of its age (along with various other facts of note) by analyzing what it’s made of.