Hematite Gemstones - Also spelled as Haematite gems
Introduction
Hematite, which is also spelled as Haematite, is one of several iron oxides, which are found in their mineral forms. This is a gemstone that crystalizes in a Rhombohedra lattice crystal form, and has an almost identical crystal structure as that found in Corundum and Ilmenite. Hematite and ilmenite crystalize into a solid foundation when at high temperatures, usually above 950 degrees Celsius.
Hematite, as a mineral, has a silver gray to black color that resembles steel; at times it is brown, red or reddish brown. It is the main ore out of which iron is extracted. You will find different varieties such as the specularite, which is actually specular hematite; marmite, which is a pseudomorph following magnetite; and kidney ore. Although these are many forms of hematite, they all have a streak that is rusty red in color. Hematite has a hardness greater than that of iron, but is said to be more brittle and breaks easily. Maghenite is a variant that is related to both magnetite and hematite.
Hematite is found in huge deposits within banded formations of iron. The Yellowstone National Park in North America is an area typical to those where hematite can be found, because the mineral is found in place where there is standing water or hot mineral springs. Hematite precipitates out of the water and is deposited in layers which are found at the bottom of the standing water, spring or lake. It is also possible for hematite to be formed through volcanic action.
It is also possible to Get hematite being formed through the weathering process in the soil, where it is formed as a secondary mineral, and together with other oxyhydroxides such as goethite or iron oxides, is the one that causes most tropical, ancient or other highly weathered soils to have that distinctive red color.
The etymology of hematite gems
Hematite is a name that is derived from the word Haima, which is Greek for blood. This is because hematite is red in color. Rouge is a powdered form of hematite used for cosmetics. Hematite has a lovely red color which lends itself to the making of pigments. It is possible to trace the English name of this gemstone to the Middle French word, Hämatite Pierre, which in itself comes from the Latin words Lapis Hämatites; these in turn came from the Ancient Greek words haimatites lithos, which literally means blood-red stone.
The history of hematite gemstones
It is due to the varying amounts of hematite in the clay, that ochre has its different colors; the percentage amount varies from 20 to 70. Anhydrate hematite is the one that is responsible for the red color of red ochre, and hydrated hematite is the one that is responsible for the yellow color of yellow ochre. The main use for ochre, through the years has been for permanent tinting in the respective colors.
In the earliest writings that are known to be made by early man, were made using red chalk which was hematite. It has been found that the powder from this mineral was used by the Pinnacle-Point man, over 164,000 possibly to social uses. It is also possible to find hematite remains in graveyards that are dated to have been dug over 80,000 years ago. In Poland, near Rydno and in Hungary near Loivas there are Paleolithic red chalk mines that are said to have been dug in around 5,000 BC, and that they belonged to the Upper Rhone culture of Linear Pottery. The Etruscans have also exploited, for many years, the rich hematite deposits on the island of Elba, and these are still there to this day.
The magnetism of hematite
Hematite is a material that has antiferromagnetic properties at below the Morin Transition, which is at 250 degrees kelvin, which is also about -9.7 degrees Fahrenheit. It has canted antiferromagnetic, or weak ferromagnetic properties above this transition point, which is also the Neel Temperatures of 948 degrees Kelvin; above this temperature, hematite is found to be paramagnetic.
There was a lot of controversy, in the 1950s, over the magnetic structure of A-hematite; some said that it could be ferromagnetic at the Curie temperature of 1000 degrees kelvin but for an extremely small moment in time. There was an added surprise; there seemed to be an added transition, with every drop in temperature at about 260 degrees kelvin, to a phase where there was no magnetic moment.
The system is basically antiferromagnetic, as has been shown, but that there is a moment when the low symmetry of the cation sites, will allow for a canting, caused by spin-orbiting between couples, when they are in the perpendicular plane to the C axis. The moment later disappears with every decrease in temperature below 260 degrees Kelvin due to a change in the anisotropy, which is initially responsible for the developing of the moments when they align to the C axis.
Spin canting does not affect or reduce the energy when in this configuration. There is a huge difference in the magnetic properties of small pieces and large bulk amounts of hematite. One notable example is the fact that the Morin Transition Temperature of this mineral will decrease with the decrease in the size of the particles. It is also possible to see the suppression of the Morin point in the nanoparticles of hematite; this has led to the belief that water, impurities and defects in the crystal structure contribute to the lack of a Morin Transition point.
Hematite can be classified as one of the complex solid mixture oxyhydroxide, which has varying amounts of water, vacancy substitutions and hydroxyl groups, and these are the ones that affect the magnetic and chemical properties of the resultant crystal. There are two other members usually referred to as hydrohematite and protohematite.
It is possible to increase the magnetic ability of hematite by simply dry-heating a ferrihidrite, 2-line, precursor, which has been prepared from solution. It is possible to get magnetic values that range from 289 to 5,027 Oe, which is usually dependent on the temperatures of the solution. The source of these high coercivity values, has been thought to be as a result of the structure of the sub particles, which is caused by the difference in the particle and crystallite size growth rates as the temperatures keep going up. The different growth rates seen in the hematite causes a development of progressive sub particle structure at the level of the nanoparticles. Single particles tend to crystalize at low temperatures ranging from 350 to 600 degrees Celsius; however at high temperatures of between 600 and 1,000 degrees Celsius, there is the growth of crystalline aggregates, which have a sub particle structure.
Hematite found in mine tailings
In the waste tailings of iron mines, you will find deposits of hematite; there is a new technology that has been developed, and is called magnetation, which uses magnets to pull out waste hematite from the old mine tailings. This is a process that is quite popular in large Mesabi Range, Iron District in Minnesota. In traditional Swedish houses, there was a paint that was commonly used, and it was made out of the Falu Pigment. In the early days, this pigment was brought from the mine tailings of the Falu Mine, and this is why the paint was given this name, even when it is no longer made of pigment from the said mines.
Hematite found on mars
There are images that have been sent back by the Mars Exploration Rover, which shows spherules of hematite which have been partly embedded in the rock, where the Opportunity landed. The NASA Mars Global Surveyor (MGS) and the 2001 spacecraft called the Mars Odyssey, which orbited the planet sent a spectral signature of hematite which was picked up by the infrared spectrometer that both vessels had. There are two sites on the planet that have an exceptionally high amount of hematite. The site near the equator of the planet, called the Terra Meridiani site, and another near the Nalles Marineris, called the Aram Chaos site. These were not the only sites, since the Aureum Chaos site also had hematite but in considerably lower deposits.
Terrestrial hematite is normally formed through environments that have water, or the so called aqueous alteration process. The fact that the mineral has been found on the planet mars was quite interesting and this resulted in another exploration rover being sent to the Terra Meridiani region, which was called Meridiani Planum.
On-site investigations by the rover sent by Opportunity showed that there was a large amount of hematite which was mainly in the form of small spherules, which were informally nicknames "Blueberries" by the scientists on this mission. The analysis of the spherules showed that they has been formed by a water solution. It is this investigation of hematite which has led them to believe that there may have been water on the planet, and that it can somehow support life.
Hematite used for jewelry
During the Victorian Era, the popularity of hematite as an item of personal adornment was at its highest. The Armenian Bole, and other types of hematite or clay that was rich in iron oxide was used in gilding. Hematite was also used to create great works of art such as the Intaglio Engraved gems. There is a synthetic material sold as magnetic hematite and it is called hematine.
The chemical properties of hematite
Generally, hematite is considered to be an oxide mineral of iron. With a formula of Fe2O3. It also has a Strunz classification of 04.CB.05. It has a Trigonal hexagonal scalenohedral crystal symmetry. It is a metal that has a Metallic grey, dull color, which also ranges all the way to a bright red color, which is typical to red ochre. It forms crystals which are tabular and thin, and in rosettes or mica, or platy formations. They are radiating fibrous, stalactitic, botryiodal or reniform masses. They are also said to be oolitic, granular earthy and columnar.
Hematite has lamellar and penetrating twinning and no cleavage. It may part at 0001 and 1011; it has an uneven to sub-conchoidal fracture and it is quite brittle. On the Mohs scale, it has a hardness value ranging from 5.5 to 6.5, and it has a splendent to metallic luster. All Hematite stones have a bright to dark red streak. It is opaque in nature and has a specific gravity of 5.26, and has uniaxial optical properties. Sometimes it shows a pleochroic nature of brownish red changing to yellowish red. It has a refractive index ranging from 2.870 to 3.220, and a birefringence of 0.280.
Traditional uses, legends, and myths of Hematite
Hematite is said to be soothing and calming, and it is therefore used to balance emotions and the state of the mind of the wearer. It is also said to absorb negative energy and encourage the wearer to aim higher when it comes to their desires, dreams and hopes. Hematite is a beautiful gemstone that is based on the mineral iron, and it can have a luster that ranges from shiny black to silver grey. Apart from these metallic colors, hematite can also be found in a brown, red, or light red color, which is the reason why the mineral was christened hematite, brought forth from the Greek word Haima, which means blood.
Since time immemorial hematite has been used as a means of decorating the body, writing, decorating walls amongst other uses that required some permanent tinting using pigments. It has been shown that cultures such as prehistoric man, the Aztecs, and Egyptians, used hematite quite a lot for these same purposes.
Hematite is a quite heavy and it is perfect for the making of cameos and figurines. This is a gemstone that was widely used in the Victorian Era and was very popular as a means of showing that one was in mourning. In the last 50 years or so, it has become very popular in North America; the converse is true in Europe, where it has been in fashion for a long time and its popularity has gone down.
In summary
This is an opaque gemstone, and its beauty is brought out when it is polished into a highly metallic luster. Normally it is cut into cabochons, but at times it is also faceted using the square or round cuts. When it is faceted, it can be truly mesmerizing, since the metallic luster allows for a truly amazing play of light reflected from the various facets of the gemstone.
Hematite is much durable than iron, bit on the other hand, it is more brittle. This is a gemstone that can be formed by volcanic action, or by the stagnation of ancient water, which are found in areas where the ground has high temperatures, such as hot springs, and volcanic lakes.
In 2001, the NASA spacecraft named Mars Odyssey, came back with a discovery that hematite existed on Mars. This discovery made scientists deduce that there must have been water on the planets of mars, which would allow for the formation of this mineral.
As far as gem quality hematite is concerned, some of the best deposits can be found in Italy and Switzerland, and there are large qualities that have also been found in Minas Gerais in Brazil. The Barrow- in- Firness, in Cambria and the Forest of Dean, are the main areas in the UK, where hematite is found in gemstone quality.
