Pigment Information: Hematite
Common Names (mineral): Blood Stone, Hematite, Red Hematite, Red Iron Ore, Red Iron Stone Common Names (pigment): Bole, Caput Mortum, Indian Red, Pompeian Red, Red Ochre, Sinoper, Sinopis, Terra Pozzuoli, Tuscan Red, Venetian Red Color: Red Colour Index: Pigment Red 101 (77491) (77015) (77492) (77538) ASTM Lightfastness: Oil: I Acrylics: Not Tested Watercolor: I Hardness: 5.5-6.5 Density: 5 Chemical Formula: Fe2O3
Hematite is a ferric oxide native earth and the principle coloring agent in red ochres, such as Indian Red, Terra Pozzuoli, Venetian Red, etc. These pigments are basically hematite associated with varying proportions of mineral impurities such as clay, chalk and silica. They differ from yellow and brown ochres by not containing water. In other words, the iron to which they owe their color is ferric oxide not hydrated ferric oxide. Cappadocia yielded to the ancient Greeks some at least of their sinopis, or red ochre. The word hematite comes from the Greek word hema, meaning blood and was given the name "bloodstone" in ancient Greece (Theofrastus, c. 325 B.C.), implying that the mineral is blood red in color. Ancient superstition held that large deposits of hematite formed from battles that were fought and the subsequent blood that flowed into the ground. When found on the surface, it is usually brown in color. Other varieties of iron oxide in the hematite category are ilmenite (FeTiO3) and magnetite (Fe3O4). Hematite is an important ore of iron and its blood red color in the powdered form lends itself well as a pigment. In nature hematite rarely occurs as crystals but usually as nodules or earthen masses. The color of the crystalline form varies from steel-gray to black, while crypto-crystalline hematite is dull red to bright red. This common mineral is found in deposits of the most diverse types. There are several varieties of hematite, two of which are suitable for use as pigments: oolitic hematite, which is a friable earth composed of small rounded grains of dark red color that are lustrous and greasy to the touch; and hematite rose, a fine-crystalline and crypto-crystalline form of hematite of red color, which are usually encountered in friable earthen masses or reniform aggregates of bladed crystals in a circular arrangement giving the appearance of a rose.
Preparation and Alteration: In the pigment trade, a synonym of hematite is iron minium (not to be confused with lead minium, an artificially made pigment of orange red hue). From our point of view, if we speak about natural mineral pigments, then it is more accurate to refer to natural iron oxide pigments not as minium, but hematite, in accordance with established classification of mineral forms . A simple test for the purity of hematite pigment can be made by observing its characteristic property to form a metallic, steel colored ball when a drop of water is placed upon the dry powder pigment.
Origin: Hematite of excellent quality is found in the deposits of Krivoy Rog and Kerch, Russia, which is where we obtain our mineral for manufacture into pigments. Ours is pure hematite consisting of nearly 95% iron oxide. Because of this it has good tinting strength and is fairly opaque. Besides pure hematite as pigment, hematite is also found as part of other mineral species, namely a pigment called mummy in Russia. Depending on the substratum it occurs, as in the case with ochres, we have identified several varieties useful as pigments: clay mummy, red iron mummy and bauxite mummy. Pigments from the natural mineral hematite are mostly, pure products of dark hue, and as such is as equally permanent and dependable as those artificially made. The hematite pigments we make vary from deep brownish red (Red Ochre) to dark reddish purple (Caput Mortum). Zinc white and hematite yield excellent flesh tints. Mixtures of Alizarin Madder and hematite were offered as Tuscan Red or Pompeian Red, according to F. W. Weber. The Alizarin Madder in this mixture does not decompose as is likely when mixed with hydrated iron oxide pigments such as ochre, sienna and umber.
History of Use: Hematite is among the oldest pigments known to humankind and has been used by every major civilization.
Permanence and Compatibility: Pigments made from the mineral hematite are dependable in mixtures with all other permanent pigments, and are considered to be permanent with considerable tinting strength and opacity. They do not react with solvents, and are indifferent to alkalis, but are partially soluble in acids.
Absorption and Grinding: Hematite absorbs a small amount of oil when ground into this binder, and forms a good film in oil painting technique.
Toxicity: The pigment is considered non-toxic, but care should always be exercised when handling the dry powder pigment so as not to inhale the dust.
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