sienna(redirected from siennas)
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, mixture of varying proportions of iron oxide and clay, used as a pigment. It occurs naturally as yellow ocher (yellow or yellow-brown in color), the iron oxide being limonite, or as red ocher, the iron oxide being hematite.
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Any of various yellowish-brown earthy substances consisting of hydrated iron oxide occurring in limonite; becomes orange-brown when burnt and is generally darker and more transparent in oils than is ocher; used as pigment for oil paints and stains.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
A naturally occurring pigment, chiefly oxides of iron; yellow-brown when mined. When calcined, a dark, rich color; then called burnt sienna.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
1. a natural earth containing ferric oxide used as a yellowish-brown pigment when untreated (raw sienna) or a reddish-brown pigment when roasted (burnt sienna)
2. the colour of this pigment
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005