Asbestos

| Home | | Pharmacognosy |

Chapter: Pharmacognosy and Phytochemistry : Drugs of Mineral Origin

Asbestos is a naturally occurring mineral which differs from other minerals in its crystal development. The crystal formation of asbestos is in the form of long thin fibers.


ASBESTOS

 

 

Source

 

Asbestos is a naturally occurring mineral which differs from other minerals in its crystal development. The crystal formation of asbestos is in the form of long thin fibers.

 

Geographical Source

 

Asbestos deposits can be found throughout the world and are still mined in Australia, Canada, South Africa, and the former Soviet Union.

 

History

 

Over the years, asbestos had many uses. Its primary use is as an insulator or fire retardant, but can also be used as a binder. Due to this versatility, asbestos can be found in many types of building materials. Even though the federal government placed a moratorium on the production of most asbestos products in the early 1970s, installation of these products continued through the late 1970s and even into the early 1980s.

 

Description

 

On the basis of the crystalline structure, asbestos are divided into two mineral groups, as serpentine and amphibole. The amphiboles, in their fibrous form are friable and so are the most carcinogenic, Serpentines have a sheet or layered structure, whereas amphiboles have a chain-like structure. Chrysotile (A, B) is the most common type of asbestos among serpentine group. There are five types of asbestos in amphibole group and they are: Amosite, Crocidolite, Anthophyllite, Tremolite, and Actinolite.

 

Chrysotile or white asbestos is obtained from Canadian serpentine rocks. It is commonly used in industries. As it is less friable it is less likely to be inhaled. One of the formula

 

given for Chrysotile is Na2Fe2+3Fe3+2Si8O22 (OH)2. Amosite is also known as brown asbestos or Grunerite

 

is an amphibole from Africa and the formula given for Amosite is Fe7Si8O22(OH)2.

Crocidolite or blue asbestos is amphibole from Africa and Australia. It is considered to be most dangerous type of asbestos and the formula given for Crocidolite is Na2Fe2+3Fe3+2Si8O22(OH)2.

 

Anthophyllite, Tremolite, and Actinolite have their formula (Mg, Fe)7Si8O22(OH)2, Ca 2Mg5Si8O22(OH)2, Ca2(Mg, Fe)5Si8O22(OH)2, respectively. They are less used industrially but are found in a variety of construction mate-rials and insulations and also in some consumer products, such as talcum powders.

 

Chemical Constituents

 

It is a double silicate of calcium-magnesium with little amount of iron which gives colour to asbestos.

 

Uses

 

It is used as filtering medium for caustic alkalies, for bacterial filters, heat resistant insulators, proof gloves, break lining, and fire-proof clothing.

 

Contact Us, Privacy Policy, Terms and Compliant, DMCA Policy and Compliant

TH 2019 - 2023 pharmacy180.com; Developed by Therithal info.