The system contains two separate tests, one test identiﬁ es the magnesium found in chrysotile and the other test detects iron found in crocidolite or amosite. An unknown containing more than 1% asbestos results in a positive reaction.
Chrysotile is gray to white and tends to be ﬂuffy. This type of asbestos rarely has the long, straight, sharp ﬁ bers associated with crocidolite or amosite. Many insulations in the United States will contain mostly chrysotile with a small amount of the more expensive amosite added as a bonding ﬁ ber.