Why does my mineral sunscreen leave a white cast?

Zinc oxide and titanium dioxide are inherently white pigments. Newer 'invisible' or 'sheer' mineral formulas use micronized or coated particles plus iron-oxide tints to reduce the cast, but verified-purchase reviewers consistently report that the deeper your skin tone, the more likely you'll see some residue with non-tinted versions. Tinted fluids like the La Roche-Posay Anthelios mineral line tend to perform better on medium-to-deep tones.