Hematite is a common iron oxide compound, having the formula Fe2O3. It is widely found in rocks and soils, occurring in various colors from black to reddish-brown. There are different varieties of hematite, such as kidney ore, martite, iron rose, and specularite.
Have you ever wondered if hematite is magnetic? In this article, we are going to discuss just that. We will look at the properties and uses of hematite. We will talk about its interesting magnetic nature. Finally, we will also discuss briefly hematite jewelry.
Is Hematite Magnetic or Non-magnetic?
Hematite can be either magnetic or non-magnetic. Depending on the temperature, hematite exhibits three different magnetic states, and this had been a subject of much scientific debate during the mid-20th century.
Let us first try to learn what magnetism is. Magnetism is a force caused by the motion of electric charges. Every substance is made up of atoms. These atoms have electrons (particles that carry an electric charge) that circle the atom’s center, called the nucleus.
In some substances like iron, electrons spin in the same direction. This allows their magnetic fields to combine and produces a magnetic field extending beyond the atoms. These objects are strongly attracted to magnets and are called ferromagnetic.
However, in most substances, equal numbers of electrons spin in opposite directions. This cancels out their magnetism, and they are not attracted to a magnetic field. These include things like paper, cloth, wood, etc., and are called diamagnetic.
Hematite is an interesting material when it comes to magnetism. Unlike most elements, hematite’s magnetism is not constant. Instead, it shows three different types of magnetic properties, depending on the temperature, as discussed below.
Does a Magnet Stick to Hematite?
Yes, hematite can stick to a magnet when the conditions are suitable to make it a ferromagnetic material. However, at other times, hematite also acts as an antiferromagnetic material or a paramagnetic material.
The magnetic properties of hematite were a subject of much scientific discussion during the mid-20th century. This was because it acted as a ferromagnetic material at temperatures over 1000 K (730°C), although with an extremely small magnetic moment (0.002 Bohr magnetons).
But, surprisingly, hematite seemed to have no net magnetic moment at temperatures under 260 K (13°C). Scientists have finally concluded that hematite shows three different forms of magnetism at different conditions.
Below the Morin temperature of 250 K (−23 °C), hematite acts as an antiferromagnetic material. This means that the spins of its atoms align in opposite directions, becoming antiparallel to each other.
So, they effectively cancel each other’s magnetic moments, resulting in a zero net magnetic moment. So at this phase, hematite is not attracted to a magnet. However, this changes with a temperature change.
At temperatures above the Morin temperature, hematite acts as a weakly ferromagnetic material. So it is weakly attracted to magnets. Finally, when the temperature goes over the Néel temperature, hematite becomes a paramagnetic material, again getting weakly attracted to magnets.
So, whether or not hematite sticks to a magnet depends on the surrounding conditions.
Is All Hematite Jewelry Magnetic?
No, not all hematite jewelry is magnetic. Hematite is a naturally occurring material that is found in different forms, some of which are magnetic while others are not. Depending on its crystal structure and temperature, hematite shows different magnetic states.
Most commercial hematite jewelry is non-magnetic, as they are made from natural, non-magnetic variants of hematite beads/chips. These non-magnetic varieties of hematite may still have some iron oxide content, but the crystal structure does not exhibit magnetic behavior.
In the jewelry world, hematite is valued for its metallic luster and color (ranging from gray to black to reddish-brown). Since it is naturally available, it is common and less expensive too.
However, there is also synthetic jewelry that is made by grinding hematite and adding a binder to create beads. This kind of hematite jewelry is often magnetic. It is considered a healing stone by many and is used for magnetic therapy purposes.
Check out this video by Crystal Meanings to learn about the healing properties of hematite.
Is Rainbow Hematite Magnetic?
No, rainbow hematite is not magnetic in its natural form. However, some rainbow hematite can be treated or coated with magnetic material to make it magnetic. This is often done in magnetic therapy.
Rainbow hematite is a type of hematite (Fe2O3) that has a variety of colors, ranging from metallic silver to iridescent purples, blues, and greens. Because of its beauty, it is also known as titanium hematite or specularite.
Rainbow hematite is not magnetic in its natural state as it has the crystal structure of alpha-Fe2O3. As discussed above, in this variant of hematite, the atoms align themselves in opposite directions, leading to no net magnetic moment.
However, rainbow hematite can become magnetic if it is treated synthetically with magnetic material. This is often done for healing purposes & magnetic therapy; such magnetite is often called power magnetite.
Does Hematite Conduct Electricity?
Hematite has a relatively low electrical conductivity. Although it does contain iron, it is primarily an oxide mineral, whose structure makes it a poor structure of electricity. However, the impurities present in hematite can still make it conductive.
Hematite is an iron oxide compound with the formula Fe2O3. Generally, minerals that have metallic properties are good conductors of electricity. Non-metallic minerals (such as quartz), on the other hand, are usually poor conductors.
Although hematite contains iron (a metal), it is primarily an oxide mineral. This means that its oxygen and iron atoms are bonded together, and this oxide structure makes it a poor conductor of electricity.
However, the impurities present in the crystal structure of hematite can still give it some degree of conductivity.
Uses of Hematite
These are the uses of hematite:
- Iron Ore: Hematite is one of the most important sources of iron ore, which is especially used to make steel. In turn, steel is used in a wide range of applications, such as construction, transportation, and manufacturing.
- Pigments: Hematite is used as a pigment in paint, ceramics, and other materials. The mineral’s reddish-brown/black coloration makes it a useful natural pigment and it can be used as an alternative to synthetic pigments.
- Jewelry: Hematite is a popular jewelry material. Its dark color & distinctive metallic luster make it an attractive choice for bracelets, necklaces, and many other accessories. Hematite is also believed to have healing properties and is used in magnetic therapy.
- Magnetic Materials: Hematite’s magnetic properties are incredibly useful in many applications. Magnetic tapes, disks, and other data storage media contain small particles of hematite that are magnetized to store digital information.
- Abrasives: Having a value of 5.5-6.5 on the Mohs Scale, hematite is a hard mineral, and it can be used as an abrasive material in sandpaper, grinding wheels, and other applications. These abrasives can be used to shape and polish a variety of materials.
Properties of Hematite
These are the properties of hematite:
- Appearance: Hematite’s color ranges from black or steel-gray to brownish-red. Its name comes from the Greek word “haima”, which means blood, referring to the reddish-brown color that some specimen exhibit. Although different varieties of hematite (kidney ore, iron rose, etc.) vary in appearance, they all have a rust-red streak. Hematite is an opaque mineral that has a metallic to splendent luster.
- Occurrence: Hematite occurs in a variety of geological environments. Large deposits occur in banded iron formations, which are sedimentary rocks that were deposited in ancient oceans containing alternating layers of iron oxides and chert. These are important sources of iron ore and are found on all continents. Hematite is also in found hydrothermal veins and can also be formed as a product of weathering processes.
- Crystal Structure: Hematite has a trigonal crystal structure, meaning that it has three axes of symmetry that do not meet at right angles. The layers in the crystal structure are slightly distorted, which is responsible for the mineral’s distinctive metallic luster. The mineral usually occurs in thick to tabular crystals with no cleavage.
- Hardness: Hematite has a value of 5.5 to 6.5 on the Mohs scale, meaning that it is relatively hard and can scratch glass. Its hardness makes it useful for making abrasive materials like sandpaper and polishing compounds. But, even though hematite is harder than pure iron, it is also more brittle (can fracture with stress). It breaks with an uneven to sub conchoidal fracture.
- Chemical Reactivity: Hematite is relatively unreactive chemically, although it does dissolve in certain acids. In most environmental conditions, it is stable and is not affected by exposure to air, water, or sunlight. This property of hematite makes it quite useful in various applications, such as pigments, abrasives, and magnetic materials.
In this article, we talked about the magnetism of hematite. Unlike most materials, hematite’s magnetism is not fixed. Instead, it has several different magnetic states (antiferromagnetism, paramagnetism, etc.) depending on the temperature. We looked at the properties and uses of hematite. Finally, we also briefly discussed hematite jewelry.