Definition of "purple-black" []

• A purple pigment prepared by precipitating alizarin in combination with a metallic oxid of aluminium and iron in the right proportion to give a purple. It is very permanent. (noun)

The Century Dictionary (Public Domain)

• "Best known as the purple-black background to many ancient American Indian drawings or petroglyphs in the southwestern United States, the varnish coats rocks in arid climates."
• "Approaching Sonoma, I see roadside fields of vines heavy with purple-black grapes, and through the town squat palms line the streets like upended joints, cartoonish and mocking."
• "Those gorgeous purple-black clusters are a sure sign that fall is nigh."