Ocre
Ocre is a natural pigment composed of several mineral elements. It may be mixed in its natural state, or artists may have intentionally blended different elements to create a specific color. Recent research on ochre focuses on identifying the specific elements of the pigments, which can help archaeologists determine the source of the pigments and give information on long-distance trade. Let’s take a closer look at what this pigment has to offer.
Red ochre
A small concentration of hematite in South Africa represents the earliest known use of red ochre by Neandertals. This material probably traveled dozens of kilometers in a single journey and entered the matrix of the site as drops of ochre-rich liquid. While these small concentrations provide a limited window into the use of red ochre by Neandertals, they do not compare to the ochre deposits found in Blombos Cave, South Africa.
The color red ochre has many names. Some examples are Venetian red, English red, Indian red, and Pozzuoli red. Its consistency and adhesion to surfaces make it an excellent crayon base. The mineral ochre is naturally occurring and occurs in soil and rocks of many different colors. It is also the closest pigment to the infrared spectrum, which gives us a sense of heat. As a result, red ochre is also associated with fire and warm blooded mammals.
Despite the ambiguity of its use, red ochre is found in burial contexts around the world. Early coastal natives of Texas used it to imbue the departed with symbolic blood. Red ochre stains shell artifacts and bone elements, and traces of the dye have been found on human bones at the Mitchell Ridge archaeological site. Researchers are not sure how the dye was produced but believe it was a part of the burial ritual.
Early ochre pigment was used for painting bodies and bones in burial rituals around 350,000 years ago. In 2008, archaeologists found the first ‘painting kit’ in the Blombos Cave, east of Cape Town, South Africa. They found a stone and a shell that were used to grind red ochre and bones into a fine powder. The ground material was then mixed with a liquid inside a large seashell. The earliest form of red ochre paint was therefore created during this time.
Ochre was used throughout history by humans. Prehistoric cave paintings have been discovered that depict ochre shades. As a light-fast pigment, ochre has a long history of use. Its vibrant shades were used in the decoration of walls, figurines, and other objects. Modern ochre has mostly replaced its natural counterparts. There are other pigments, however, but the natural ochre is the most commonly used.
Hematite
The history of Ocre hematite can be traced to the ancient Native American cultures. This reddish-brown mineral is a product of weathering of iron-bearing minerals, which can be black or grey. It is a hydrated iron oxide that is commonly found in iron mines. Ocre is a symbol of life and is associated with the signs of Aries and Aquarius. Red ochre was a popular pigment used by many civilisations for many thousands of years. Its widespread use has led to a significant amount of research. X-ray fluorescence was used to determine the chemical composition of ten biological and manufactured artefacts. The results of this analysis were used to establish that ochre from the ancient world is a form of hematite.
Hematite is found in some iron ore deposits. Its mining and use dates back 13,000 years. In North America, it is rare. Its use as paint rocks and for drawing purposes has been documented. It is mined from an iron ore deposit and forms in the earth. This type of hematite has been discovered in five sites. This discovery suggests that human civilizations may have used ochres to trade iron ore.
Ocre is a natural clay earth pigment that ranges from yellow to deep orange. A typical ochre is light brown to yellow, but can also have a reddish tint. When large amounts of hematite are present in the ochre, it becomes a reddish colour. Ocre is one of the oldest pigments known to man. Its use is far reaching, and it can safely be mixed with other pigments. It varies in its transparency and value, with some forms being opaque and valuable for glazing.
Ocre has been used for thousands of years by artists, both ancient and modern. Ocre-pigmented images can be found on prehistoric cave walls and medieval paintings. The ochre pigment is derived from hematite and limonite, two secondary oxidized iron minerals. The process of weathering produces the red and yellow iron oxide minerals. The clay hills of Provence have long been a major source of ochre pigment.
Ocre hematite was used as a pigment in oil paints. Its oil content, which is related to palmitic acid, was studied using GC-MS analyses. In addition, it contained oleic and stearic acids. Both fatty acids were present in trace amounts in linseed oil paint mock-ups. This is a significant finding for the composition of Ocre hematite pigments.
Goethite
The yellow earth mineral goethite is a diaspore group iron(III) oxide-hydroxide. It occurs in low-temperature environments and has long been used for its color. Paint pigment samples found in Lascaux, France, contain goethite. The mineral has been mined in the Czech Republic, Germany, and Saxony. Goethite is soluble in mineral acids but insoluble in water.
In the Middle Stone Age, goethite was heated and used as body paint. It was also used for rituals and art. Its pigments were so vivid that they were seen as life. The process of heating ochre began around 100,000 years ago in the middle stone age. Goethite gradually turned orange-yellow, while haematite quickly became red. This process produced the vibrant red pigments we know today.
Goethite is found in several deposits around the world. The South African deposits contain goethite, which is the main ingredient in iron rust. It is found in the southern Appalachians, Brazil, and Russia. It ranges in color from yellow-brown to red-brown. Calcinating goethite to 500-600degC results in the most intense red tones.
Goethite is a dark brown crystal that has the same chemical formula as Limonite. Limonite is a bright yellow or red ochre. Both pigments have been used as a cosmetic and paint pigment. Its color is also dependent on the chemical makeup of the rock. A crystalline goethite is a great choice for many applications. Once it is ground to a fine powder, it can be used in paint.
The process of making goethite is different from that of the synthetic kind. It requires more precise control of temperatures, and ancient people probably did not use crucibles to heat it. Instead, they could have sandwiched the powder between two stones or heated it in coals. This would have required a very sophisticated method of heating. The results would not be visible until it had cooled completely.
While ochre is commonly perceived as red, it is actually a naturally occurring yellow mineral pigment. It is comprised of clay, siliceous materials, and iron oxyhydroxide. The pigment has an odor and can range from light yellow to a deep red. It is the primary component of ochre earths and the main component of limonite. Similarly, it is compatible with other pigments and is frequently mixed with other colorants to create a more complex color.
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