Cristobalite as a pigment substitute and as a composition enhancing mineral, compositions containing the same, and articles and coatings prepared with such compositions

A method of preparing cristobalite, the method comprising:

• (a) mixing a whole grain silica and a fluxing agent to form a first mixture;
• (b) processing the mixture through a reaction apparatus at a temperature within a range from 1000° C. to 1200° C. for a time period within a range of 0.5 to 2 hours to obtain cristobalite;
• (c) filtering the cristobalite through a mesh screen to remove granules larger than 10 to 30 mesh;
• and
• (d) grinding unfiltered cristobalite to a powdered cristobalite comprising a d50 particle size within a range of from 1 μm to 15 μm, and wherein the powdered cristobalite comprises a silica density within a range of from 2.2 to 2.3 g/cm3 and a cristobalite fraction determined by x-ray diffraction is greater than 75%.

A cristobalite comprising:

• a d50 particle size selected within a range of from 1 μm to 15 μm;
• an L color coordinate of greater than 96;
• an a color coordinate of less than 1;
• and
• a b color coordinate of 1 or less,
• wherein the cristobalite is a powder, and
• wherein the cristobalite has a loose bulk density of about 40.0 lbm/ft3 and a tap bulk density of about 70 lbm/ft3 at a d50 particle size of 15 μm, or a loose bulk density of about 20.0 lbm/ft3 and a tap bulk density of about 40 lbm/ft3 at a d50 particle size of 2 μm.