Description
Armenian Purple Ocher is a natural earth containing clay tinted by iron oxide, giving an exceptionally cool purple-reddish hue. Our Armenian Purple Ocher contains about 13% iron oxide and 49% silica. Purple Ocher is obtained from iron ore deposits near Lori, Armenia.
Source
Purple ocher is a natural earth containing clay tinted by iron oxide. It is composed of a naturally calcined form of hematite and traces of gypsum (calcium sulfate) or calcite (calcium carbonate). Hematite is a mineral composed of iron oxide minerals (α-Fe2O3) that occur as natural earth. Red ocher varies from deep red to brownish red depending upon the content of iron oxide and other minerals. Red iron oxide minerals, such as hematite, are found worldwide and have been used as pigments since prehistory.
Permanence and Compatibility
Purple ocher is among the most permanent colors on the artist’s palette. It is compatible with all other pigments and can be used with good results in all mediums.
Oil Absorption and Grinding
Purple ocher absorbs a medium amount of oil (see table below), which may slow the drying of oil paint, but because iron oxide is a drier in oil, it dries fast and forms an excellent film.
Toxicity
Purple ochers are not considered toxic, but care should be taken in handling the dry powder pigment to avoid inhaling the dust.
| Pigment Information | |
| Color: | Purple |
| Colour Index: | Pigment Red 102 (77491) |
| Chemical Name: | Iron Oxide |
| Chemical Formula: | α-Fe2O3 |
| Chemical Composition | |
| SiO2: | 58.67% |
| Al2O3: | 17.06% |
| Fe2O3: | 11.22% |
| MgO: | 0.12% |
| CaO: | 0.59% |
| ASTM Lightfastness Rating | |
| Acrylic: | I |
| Oil: | I |
| Watercolor: | I |
| Properties | |
| Bulk Density: | 0.56 g/cm3 |
| Oil Absorption: | 35 g/100 g |
| Particle Size: | 0 to 15 microns: 80-85% 16 to 29 microns: 15-20% 30 microns and above: 0.1% |
| Residual (Mesh 325): | <0.1% |
| pH: | 8.5 |
| Thermal Color Stability: | <850 °C |
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