Types of Asbestos: properties of Amphibole, Chrysotile, Crocidolite, Amosite, Anthophyllite & Tremolite Asbestos
Properties of Amphibole Group Asbestos
A review will also be made of the
amphibole group of minerals which is generally identified
by the formula 2CaO.5MgO.8SiO2H20. The actual composition
of the amphibole fibers varies greatly, particularly in
comparison to chrysotile.
[Click to enlarge any image]
The variation in composition
results in a physical property change of the fibers. This
variation requires more rigid controls for obtaining and
identifying shipments of amphibole fibers.
Properties of Chrysotile Asbestsos
Chrysotile asbestos in rock form is usually
found in soft shades of green; these shades range from a
very pale green to a dark green. The Arizona asbestos is
often pale yellow.
However, despite its original color, it in-
variably becomes white or grayish white when it is opened
or fiberized. Its commercial usefulness depends not so much
on its chemical composition but on its physical properties.
For textile products, chrysotile asbestos is the most important type of asbestos used because it has the best combination of strength and
flexibility. Its resistance to alkalies is very good. However,
its resistance to acids is lower than that of other varieties.
its specific heat is 0.266 Btu per lb per °F.
From the point of view of structure, chrysotile asbestos is considered
a silicate with a sheet structure; this factor makes
it the magnesium analog of the kaolin group. In most of
its occurrences, chryso'tile which has serpentine or olivine
- as its source rock, shows either none or very little ' lime.
Its chemical composition is Mg6(0H)6(S4011)H20 or
3MgO-2SiO2-2H20. Chemical composition of fibers can
vary from mine to mine, but this variation is not great when
compared to the other asbestos fibers.
Although the fibrous structure of many chrysotile fibers
is similar, there is often a difference in the operation of
separating the individual fibers. Techniques and experience
are required both at the mining site and in the manufacturing
process in order to obtain good quality and fibrous
Crocidolite Asbestos Properties
Crocidolite, because of its distinctive color,
is commonly known as blue asbestos. It is easily recognized
by its blue color which appears both in its natural state and
When found in nature, the color varies
from lavender blue to dark blue. Sometimes red and yellow
streaks exist. When the fiber is opened, the dolor of the
fiberized structure is lighter in shade than in its original
form. The blue color is the result of the high soda content
or the iron compounds associated with the rock formation.
Its general chemical formula is 3Na 2 O6FeO2Fe 2 O 3 16-
Si0 2 11 2 0. Variation in the composition occurs where sodium
may be replaced by potash, ferric or ferrous iron by magnesium
or manganese and ferrous iron by aluminum.
blue asbestos occurs only in very few localities and is mined
only in large quantities in South Africa. Its predominate
properties include high tensile strength, acid resistance,
harshness and resistance to effects of outdoor exposure.
Amosite Asbestos Properties
Crocidolite as well as amosite occurs in metamorphosed
siliceous-ferruginous sediments. The fibers are
generally several inches long; however, the length is usually
of no advantage inasmuch as its greatest use involves the
manufacture of asbestos-cement products where fibers , of
% in. or shorter are used. The more important features of
amosite are its heat and acid resistant properties. In the
rock form, it is gray to gray-green but when it is opened,
it gives the appearance of a cloudy gray.
It may contain as much as 40 per cent iron oxide; sometimes,
it is compared to anthophyllite. Unlike the true anthophyllites,
amosite has long fibers and it is not as brittle.
Anthophyllite Asbestos Properties
Anthophyllite has a very limited use because
of its weak fiber structure despite its resistance to
high temperatures and chemicals.
Its low ignition loss is
comparable to that of tremolite.
It is never known to occur
with fibers that are sufficiently flexible to be spun.
Tremolite Asbestos Properties
Tremolite asbestos (shown at above left under the microscope, and at above right as fire insulation on the basement ceiling of a commercial building in White Plains, NY) generally has weak and brittle fibers;
its color ranges from gray to white.
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 Asbestos, its Industrial Applications, D.V. Roasato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposuret.pdf ].
 Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
 Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
 Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
 "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
 EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460 Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Basic Information about Asbestos, US EPA, web search 08/17/2010, original source: http://www.epa.gov/asbestos/pubs/help.html
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[copy on file as /hazmat/Vermiculite_US_EPA.pdf/ Current Best Practices for Vermiculite Attic Insulation - May 2003, U.S. EPA
[copy on file as] /hazmat/Vermiculite_Health_Canada.pdf] Vermiculite Insulation Containing Amphibole Asbestos - September 2009, Health Canada
Managing Asbestos in Place, How to Develop and Maintain a Building Asbestos Operations and Maintenance (O&M) Program, U.S. EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/management_in_place.html
Asbestos Strategies, Lessons Learned about Management and Use of Asbestos: Report of Findings and Recommendations on the Use and Management of Asbestos, 16 May 2003, US EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/asbstrategiesrptgetf.pdf
prepared by the: Global Environment & Technology Foundation, 7010 Little River Turnpike, Suite. 460, Annandale VA 20003
Other US EPA Publications on asbestos: web search 01/20/2011, see http://www.epa.gov/asbestos/pubs/pubs.html
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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