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Actinolite is a fibrous silicate mineral (amphibole) belonging to the group of double chained inosilicates. The name of the mineral comes from the Greek word “Aktis” or “Aktinos” which mean a ray or a beam.

Actinolite Chemical Formula

The chemical formula for Actinolite is Ca2(Mg, Fe)5Si8O22(OH)2. It is expressed in words as Calcium Magnesium Iron Silicate Hydroxide.

Actinolite Facts, Characteristics and Description

Actinolite Texture

Actinolites can be either compact and dense or fibrous and brittle.

Actinolite Crystal Shape

Actinolite crystals are generally elongated, prismatic and flattened in their shapes.

Actinolite Luster

Actinolite crystals have a vitreous and silky luster.

Actinolite Transparency

Actinolites can be either transparent or translucent.

Actinolite Crystal Structure

Actinolite crystals have a monoclinic structure. They have three axes with unequal lengths. They tend to form rectangular prisms with parallelogram bases. They have a splintered surface.

Actinolite Color

Actinolites come in a wide variety of colors that range from creamy white to green and green-black or grey and grey-green. Dark color varieties such as brown or black may also be found when the iron content is higher. The thin section of Actinolite can be colorless or may range from pale green to deep green.

Actinolite Hardness

The hardness of Actinolite, measured in Mohs scale of mineral hardness, falls within a range of 5.5 to 6 with an average of 5.7.

Actinolite Density

The density of Actinolite falls within a range of 3.03 to 3.24 g/cm3.

Actinolite Specific Gravity

The specific gravity of Actinolite ranges between 2.9 to 3.3, which is a bit more than the average specific gravity for translucent minerals.

Optical Properties of Actinolite

Actinolites are biaxial negative with a big axial angle and a weak dispersion. They have a double refractive index with an anomalous aggregation. Refractive index is between 1.606 and 1.641.

Actinolite Birefringence

Birefringence ranges within 0.022 to 0.027 and maximum average birefringence is 0.023.

Actinolite extinction angle

This mineral has a low extinction angle.

Actinolite Mineral Data

Actinolites are considered to be intermediate crystal formations that fall between magnesium-rich tremolite (Ca2Mg5Si8O22(OH)2) and iron-rich ferro-Actinolite (Ca2Fe5Si8O22(OH)2). In an Actinolite crystal, iron and magnesium ions can get exchanged freely. The fibrous mineral asbestos is derived from Actinolite.

Actinolite Formation

Actinolite mineral crystals frequently form in igneous rocks when they are exposed to high pressure and very low temperature. They also frequently occur in metamorphic rocks such as schist, dolomite and limestone. Actinolite is also found in metamorphosed mafic and ultramafic rocks.

Varieties of Actinolite

There are different forms of Actinolite which vary slightly in their chemical structure. Nephrite, tremolite, ferro-actinolite and byssolite are the common varieties.

Actinolite Picture
Picture 1 – Actinolite
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Tremolite Actinolite

Actinolite tremolites are a type of amphibole Actinolites. Its chemical formula is Ca2(Mg,Fe)5[Si8O22](OH,F)2. The crystal structure of Actinolite tremolite is monoclinic. It is rich in iron content. Actinolite tremolite can be colorless or can range from a pale green to dark green color.

Actinolite Schist

Actinolite schist is a metamorphic rock with a predominance of mineral Actinolite.  Actinolite schist rocks have foliation. The blades of Actinolite in an Actinolite schist rock are all aligned to each other.

Actinolite Uses

Actinolite is most commonly used as asbestos in manufacturing and industrial domains. Amphiboles are a common asbestos variety along with serpentine asbestos. Other forms of asbestos Actinolites are tremolites and anthophyllites. They make good insulation materials. Actinolites are also used in structural fire-proofing, in construction as well as for gardening purposes.

Actinolite quartz is green in color. This quartz is used for its metaphysical properties. They can be used as a protective shield to ward off negative influences. They are also believed to give spiritual guidance to its user and help an individual walk on their chosen path. For the user, it develops a strong sense of self worth and an overall sense of responsibility.

It is believed that Actinolite quartz acts as a channel for Universal Life Force and promotes growth and fertility. This is why it is often kept in gardens to promote the growth of plants and flowers.

Actinolite has healing properties. It is used as a crystal which helps in healing the different chakras of the body. The green Actinolite heals the heart chakra and brings harmony and balance of the mind. It also helps develop patience and an accepting attitude. The green Actinolite has healing properties similar to jade.

The black variety of Actinolite heals the root chakra. It helps one to achieve mental security by helping in accepting changes and adjusting well to traumatic incidents.

The Actinolite crystal helps bring the body and mind into a balance with the energies of psyche and spirit. Actinolite also enhances the color and overall effectiveness of other stones and crystals it is in touch with. The Actinolite crystal is a powerful tool for visualization, meditation and imagery.

Actinolites as Gemstones

Some Actinolites are also used as gemstones. Nephrite is used to create jade stones. They can be green or white in color. Jade is used for ornamental and spiritual purposes. Another form of gemstone called the cat’s eye is formed from the chatoyant Actinolite. The cat’s eye can be translucent or opaque and their color varies between green and yellowish green. Transparent Actinolites are rare and are used for making gems as well.

Actinolite Locations

There are many locations across the world where Actinolite is mined. Some of these locations are mentioned below:

  • Taiwan
  • Tanzania
  • Madagascar
  • Canada
  • Mt. Greiner, Zillertal, Austria
  • Untersulzbachtal, Austria
  • Zermatt, Valais, Switzerland
  • Arendal and Snarum, Norway
  • The Ural Mountains, Russia
  • The town of Gouverneur in St. Lawrence County, New York, USA
  • The towns of Newton and Franklin in Sussex County, New Jersey, USA
  • The town of Chester in Windsor County, Vermont, USA
  • Fairfax quarry, Centreville in Fairfax County, Virginia, USA
  • The town of Crestmore in Riverside County, California, USA
  • The town of Salida in Chaffee County, Colorado, USA

Where to buy Actinolite?

Actinolite can be brought from any shops selling quartz, crystals and gemstones. Alternatively, it can also be brought from online shops.

Actinolite Asbestos MSDS

Actinolite asbestos has been classified as a carcinogen which can cause cancer. An estimated 10000 deaths are caused by asbestos poisoning every year in United States. Actinolite Asbestos has been found in various materials such as:

  • Children’s toys
  • Paints
  • Joint Compounds
  • Sealants
  • Drywall
  • Ceiling and Floor Tiles
  • Cement
  • Roof Shingles

The level of Actinolite asbestos fibers are higher near an asbestos mine or a factory, or an under construction building using asbestos products or in a toxic waste site.

Accidental ingestion or inhalation of asbestos fibers results in these fibers getting embedded in stomach, heart or lungs. Once inside the body, these fibers are very difficult to get rid of and might cause cellular damage which can again lead to mesothelioma or lung cancer.  Other diseases caused by ingestion or inhalation of Actinolite asbestos are

  • Pleural diseases related to intake of asbestos fibers
  • Asbestosis
  • Laryngeal Cancer
  • Esophagus Cancer
  • Pneumoconiosis
  • Stomach Cancer
  • Pleural Mesothelioma
  • Peritoneal Mesothelioma

There are a number of methods used to treat patients infected by asbestos health hazards. Some of these are surgery, chemotherapy and radiation. Chances of effective cure depend on an early diagnosis. Hence, it is advisable to contact a doctor immediately if a family member is infected by asbestos poisoning.

Actinolite has certain characteristics due to which it might prove to be hazardous to human beings. If the necessary precautions are taken, one can avoid these health issues. These substances are great for use as gemstones and also for their healing properties. They also help in growth and mental wellbeing of a person.


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