Zinnwaldite, KLiFeAl(AlSi3)O10(OH,F)2, is a potassium lithium iron aluminium silicate hydroxide fluoride silicate mineral in the mica group.

It occurs in greisens, pegmatite and quartz veins often associated with tin ore deposits. Commonly associated with topaz, cassiterite, wolframite, lepidolite, spodumene, beryl, tourmaline and fluorite.

It was first described in 1845 in Zinnwald (now Cinovec), Czech Republic.