Absorbent, Texture Enhancer, Pigment

Average
BISMUTH OXYCHLORIDE

Also known as synthetic pearl, itŠ—Ès the primary ingredient included in most powders that are referred to as "mineral makeup."
Some cosmetic companies claim that bismuth oxychloride is natural and better for skin than talc. The truth is that in many ways talc is a more natural, unadulterated, pure ingredient than bismuth oxychloride.
Bismuth oxychloride, which seldom occurs in nature, is manufactured by combining bismuth, a by-product of lead and copper metal refining, with chloride (a chlorine compound) and water. It's used in cosmetics because it has a distinct shimmery, pearlescent appearance and a fine white powder texture that adheres well to skin.
Bismuth oxychloride is heavier than talc. Pure bismuth is a naturally occurring, grayish-white powder. It and its derivatives are used as skin protectives, thickeners, and absorbent agents.
Bismuth oxychloride was permanently listed by the FDA as a coloring agent in 1977 and for use as a synthetic ingredient.
Some people react to bismuth oxychloride due to its unique crystalline structure. What happens is that the crystals can "poke" at skin and get stuck in the pores, where the sharper "spokes" can cause irritation. This is more of a problem when bismuth oxychloride is the main ingredient in powder makeup.
Pure concentrations of bismuth oxychloride nanoparticles appear to have a negative effect on human skin cells.

References for this information:

Food and Chemical Toxicology, June 2015, pages 52-61

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=73.2162&SearchTerm=bismuth%20oxychloride

http://bismuth.atomistry.com/production.html