Tremolite

Authors: Stephanie, Kayla, and Gerardo

Mineral Name: Tremolite

Chemical Composition: (Ca₂)(Mg₅)(Si₈O₂₂)(OH)₂

Color: White, brown, colourless, gray, light green, green, light yellow, pink-violet

Streak: White/colorless

Hardness: 5-6

Cleavage/Fracture: Tremolite has a prismatic cleavage, in which the mineral breaks off into thin, vertical, prism-like crystals.(1)

Crystal Form: Tremolite is part of the monoclinic crystal system. It can come in a variety of crystal forms such as prismatic, which are typically elongated in one direction and contain at least four sides, all similar in size.(1) Bladed crystals are usually flat and can appear like the blades of a knife. Columnar are slim parallel crystals that are next to each other and are compact.(1) Reticulated crystals are long and are formed in a criss cross arrangement.(1) Fibrous crystals are very fine and parallel. Fibrous crystals usually feel soft like cloth and due to this can easily be bent.(1) The final crystal form is acicular. Acicular crystals are groups of long thin crystals.(1)

Luster: Vitreous or silky (1)

Special Features: Tremolite is a form of highly fibrous asbestos mineral. It also fluoresces red under UV radiation.(3)

Varieties(1):

  1. Chrome-Tremolite: This mineral is an emerald green color due to an element called chromium.

  2. Hexagonite: Hexagonite is mostly found in New York and can vary in color from pink to purple.

  3. Amianthus: A finely fibrous asbestos.

  4. Asbestos: This is what makes tremolite potentially fatal to those who are exposed to it and defines any mineral that is fibrous and flexible.

  5. Asbestos Amphibole: Similar to asbestos but the fibers are straighter and more brittle.

  6. Byssolite: Byssolite looks hairy due to its tiny fibrous crystals that are interwoven.

  7. Nephrite: A denser mineral made of strong and hard interwoven fibers

  8. Tirodite: Tremolite that contains manganese oxide dendrites

Mineral Group: Tremolite is a part of the calcium amphibole subgroup which belongs to the w(OH,F,CI) amphibole group.(2) This group makes up one of many groups within the overall amphibole subgroup section.(2) Tremolite is also part of the silicates group which is identified by rocks that contain the elements silicon and oxygen.(1) Finally tremolite is part of the inosilicates group that have their tetrahedrons formed in chains.(1)

Environment: Tremolite is a mineral found in both igneous and metamorphic rocks. It is a common rock-forming mineral associated with the process of contact metamorphism. This means that the metamorphism process happens while in contact with great amounts of heat, or, in most cases, within close proximity to magma. This differs from regional metamorphism which relies more of pressure than heat to initiate the change.(6) Within igneous rocks it is usually a secondary mineral formed by the weathering of the igneous rock, which can change the chemical composition of the mineralogy of igneous rocks.

Associated Rock types: Tremolite is found in contact metamorphic rock such as hornfels, skarns, and serpentinite.(1) It’s also often found in marble that is composed of metamorphosed calcite and dolomite.(1) Finally, tremolite can be found in igneous rocks as a secondary mineral such as basalt and diabase.(1)

Occurrence in North America: A variety of tremolite, such as lilac hexagonite, can be found in Balmat, Fowler, Edwards, and Richville, New York.(1) Other tremolite varieties can be found in Pennsylvania, Colorado, Washington, Wyoming, Alaska, and California.(1) Lastly, it can be found in Ontario, Canada.(1)

Economic Uses: In small quantities tremolite is a possible collectors item or can be used as a gemstone for jewelry. Jade is the term used for tremolite that is used in jewelry, tools, and other objects for more than 5,000 years.(4) It is important to note that Jade is actually a group of different types of minerals, including tremolite, but can also include actinolite and jadeite.(4) Jade is known for being tough and, because of its toughness, was earlier used for things like arrowheads and tools for hammering and scraping. It was later discovered that you can polish it down to be a beautiful decorative piece or stone for jewelry. It comes in a variety of colors including green, white, lavender, yellow, blue, black, red, orange, and gray.(4) Some people also believe tremolite to have spiritual benefits.

Industrial Uses: Tremolite, in its asbestos form, was used widely for industrial purposes until very recently. Asbestos is a set of minerals that can be found in the fibers of soil and rock. Chrysotile and amphibole are the two main types of asbestos and both have been linked to cancer.(5) Asbestos is a strong material that is heat and chemical resistant, and also does not conduct electricity, which makes it a useful product.(5) Asbestos fibers were used for insulating factories, schools, homes, ships, and many other products. During the beginning of the 20th century, it was discovered that breathing in asbestos caused scarring of the lungs.(5) During the 1930s, steps were taken to protect workers from breathing in asbestos by using a ventilation and exhaust systems.(5) However, in World War 2, many people were exposed to high levels of asbestos.(5) After cancer was linked back to asbestos, laws were set in place to protect people and reduce exposure.(5)

First Notable Identification: Tremolite was named in 1789 by Johann Georg Albrecht Hopfner for the Tramola Valley.(2) The mineral was originally called saulenspath and sternspath by Johann Ehrenreich Von Fichtel from Transylvania.(2)

How We Identified It: Tremolite comes in several sizes and colors. It can be identified by not only how fibrous the mineral is, but also its usual prism like form or shape. It will also present itself in a fluorescent orange-red color when exposed to UV radiation.

Don’t Confuse It With: Tremolite is commonly confused with actinolite and they cannot be differentiated without the use of x-ray equipment.(1) Jade can be confused with tremolite due to its green color, transparency, and luster. However, jade can be differentiated because it is harder in comparison to tremolite.(1) Epidote is also a transparent green mineral but is harder than tremolite. Jade also has a white streak while tremolite gives a transparent or clear streak.(1) Wollastonite is softer than tremolite, gives a white streak, and is reactive to hydrochloric acid.(1)



Works Cited

  1. Tremolite: The amphibole mineral Tremolite information and pictures. (n.d.). Retrieved from https://m.minerals.net/mineral/tremolite.aspx

  2. Tremolite. (n.d.). Retrieved from http://www.mindat.org/min-4011.html.

  3. Barmarin, Gérard. “Database of Luminescent Minerals.” Luminescence, Fluorescence and Phosphorescence of Minerals, www.fluomin.org/uk/fiche.php?id=716.

  4. “What Is Jade?” Geology, geology.com/gemstones/jade/.

  5. “Asbestos and Cancer Risk.” American Cancer Society, www.cancer.org/cancer/cancer-causes/asbestos.html.

  6. (n.d.). Retrieved March 7, 2020, from https://study.com/academy/lesson/contract-metamorphism-vs-regional-metamorphism-definition-differences.html