from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of a large group of structurally similar hydrated double silicate minerals, such as hornblende, containing various combinations of sodium, calcium, magnesium, iron, and aluminum.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A large group of structurally similar hydrated double silicate minerals, containing various combinations of sodium, calcium, magnesium, iron, and aluminium/aluminum
from the GNU version of the Collaborative International Dictionary of English
- n. A common mineral embracing many varieties varying in color and in composition. It occurs in monoclinic crystals; also massive, generally with fibrous or columnar structure. The color varies from white to gray, green, brown, and black. It is a silicate of magnesium and calcium, with usually aluminium and iron. Some common varieties are tremolite, actinolite, asbestus, edenite, hornblende (the last name being also used as a general term for the whole species). Amphibole is a constituent of many crystalline rocks, as syenite, diorite, most varieties of trachyte, etc. See hornblende.
from The Century Dictionary and Cyclopedia
- n. A name given by Haüy to hornblende, from its resemblance to augite, for which it may readily be mistaken: now used as a general term to include all the varieties of which common hornblende is one. See hornblende.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a mineral or mineral variety belonging to the amphibole group
Prolonged exposure to one variety, called amphibole fibers, appears to bring serious tissue damage and cancer.
That is the textbook definition, but some other typical characteristics of dacite lavas (or magmas) is the presence of certain minerals: plagioclase feldspar and hydrous minerals (containing water in their mineral structure) such as amphibole (typically hornblende) or biotite mica.
Tightly bound chrysolite, amphibole and tremolite fibres are completely safe and their manufacture and export strictly controlled, in theory, under the Hazardous Products and Environmental Protection Acts.
There is strong evidence that the genotoxic and carcinogenic potentials of asbestos fibers are not identical; in particular, mesothelial cancer is most strongly associated with amphibole fibers.
In the amphibole group, there are five types of asbestos.
From this generic representation, the chemical composition of the amphibole asbestos can be given as noted in Table 1.
The average chemical composition of amphibole minerals may be represented as:
Elemental analysis data for several chrysotile and amphibole samples are presented in the table below.
The amphiboles have a lower water (hydroxyl) content and their dehydroxylation reaction begins between 400-600° C, depending on the amphibole type; this reaction leads to a weight loss of approximately 2%.
The behavior of amphibole fibers under continuous heating is similar to that observed with chrysotile, although the temperatures of dehydroxylation and recrystallization processes are different.