UCLA researchers have developed a mineral sunscreen formulation that significantly reduces the white, chalky cast that keeps many people from wearing sun protection daily. UCLA researchers have developed a mineral sunscreen formulation that significantly reduces the white, chalky cast that keeps many people from wearing sun protection daily. Excessive exposure to ultraviolet radiation is the leading preventable cause of skin cancer, the most common cancer in the United States. Yet many Americans still skip it in part because mineral formulas with zinc oxide often leave behind a white, chalky cast. A new study led by researchers at the UCLA Health Jonsson Comprehensive Cancer Center suggests that these concerns may be fixable without inventing a new chemical ingredient.