Broad-spectrum, mineral, photoprotective compositions

A broad-spectrum, stable, mineral sunscreen composition, in the form of a water-in-oil emulsion, prepared by the process comprising:

• (1) preparing a first mixture comprising (a) porous zinc oxide particles having an average particle size of greater than 100 nanometers, (b) polyhydroxystearic acid, (c) squalane, and (d) a formulation component comprising a first film-forming ingredient comprising bis-vinyl dimethicone/dimethicone copolymer in a solvent comprising either (I) cetyl dimethicone, (II) dimethicone, or (III) both cetyl dimethicone and dimethicone;
• (2) mixing the first mixture such that the porous zinc oxide particles are uniformly dispersed in the first mixture and the porous zinc oxide particles are infiltrated by the formulation component;
• (3) homogenizing the first mixture;
• (4) preparing a second mixture comprising (a) titanium dioxide particles, caprylic/capric triglyceride, aluminum hydroxide, stearic acid, and polyhydroxystearic acid, (b) a suspending dispersant component comprising phenyl trimethicone, disteardimonium hectorite, and triethyl citrate, and (c) a second film-forming ingredient comprising acrylates/dimethicone copolymer in dimethicone;
• (5) combining the first mixture and the second mixture to form a third mixture, the third mixture further comprising at least one polyglycerin emulsifier containing 3-6 glycerin units;
• (6) mixing the third mixture until the titanium dioxide particles are uniformly dispersed in the third mixture;
• (7) preparing a fourth mixture comprising water, glycerin, and sodium chloride;
• (8) adding the fourth mixture to the third mixture while mixing the third mixture to form an emulsion, and thereafter homogenizing the emulsion to form a fifth mixture;
• and
• (9) adding two siliceous compounds to the fifth mixture to form the broad-spectrum, stable, mineral sunscreen composition, wherein the two siliceous compounds consist of amorphous spherical silica and a mixture of materials from different diatomaceous algal species, wherein each of the algal species comprises photonic and porous silica crystals, wherein the process is performed in a manner such that (i) the zinc oxide and titanium dioxide particles are uniformly dispersed in the composition, (ii) the composition does not separate into oil and water phases or experience particle agglomeration or particle settling after storage at (I) 50° C. for one month or (II) 40° C. for three months, (iii) the composition does not cause visible whitening when applied on the skin of a person having a Fitzpatrick Skin Type of I-IV, and (iv) the composition provides a sun protection factor (SPF) of at least 50.