When white is right (GC-12)
The world abounds with color, but sometimes only white is the right color. Manufactured products that require white filler of pigment materials include paints, rubber, plastics, cosmetics, pharmaceutical products, paper coatings, and a host of other important everyday items. Indiana contains many limestones with the proper chemistry for use as filler. Some appear white, but many shades of white occur. Testing at the Indiana Geological Survey determines if these limestones are white enough.

Geologists describe rock colors in the field by using a color chart. The chart is based on hue, value, and saturation. More refined measurements are made in the laboratory by a photometer or a reflectance meter. Simple calculations with these measurements allow precise determination of whiteness.

Our Hoosier State Beneath Us: Geochemistry/Geophysics


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