Zinc oxide is a white fluffy powder that comes from a natural mineral. It is commonly found in sunscreens, calamine lotion, baby powder and diaper rash formulas. Zinc oxide is probably known best for providing a physical barrier to UVA and UVB rays. It's also known for its antibacterial, astringent, anti-itch, water resistant, non-irritating, non-allergenic, non-comedogenic (won't clog pores) properties, making it ideal for use on irritated skin, chafing, poison ivy, dermatitis, eczema and abrasions.
How white it will make your skin and the possibility of absorption through the skin depend upon the size of the zinc oxide particles. Nano sized particles will not make your skin look white and may be absorbed through the skin. Non-nano sized particles will appear white on your skin and are less likely to be absorbed. The bigger the particles, the whiter they will appear. Whether absorption of zinc is an issue or not is still debated as our bodies use zinc. The concern seems to lie with high levels of zinc in the body, as in the use of zinc supplements.
(We use a non-nano zinc oxide as an option in our peppermint lip balm and as an option in our face lotions. The particle size is large enough to not be absorbed but small enough to not appear too white.)