How can you tell from enlish word or not?

[OlderAndWiser]

“'Alchemy' is from the Greek khemeioa, which was either from Khemia, a name for Egypt meaning 'land of black earth,' or the Greek khymatos 'that which is poured out.'”

uselessetymology.com/.../

[Pete671]

Most English words are mongrels, or of foreign origin, esp French, Latin, or Greek, may from India as well,,,
Alchemy is used in English but it's etymology is not,,,
My first name is Greek, surname high Dutch/German,,,