The Mineral chamosite
Chamosite is a member of the Chlorite, and it forms a series with the mineral Clinochlore.
Chamosite is the iron rich end member, and Clinochlore is the
magnesium-rich end member. Their properties are very similar, and they are difficult to distinguish from each other, though Chamosite is harder, heavier, and usually less transparent than Clinochlore.
Greenish-gray, gray, greenish-black, brown
2.5 - 3
3 - 3.4
Vitreous to pearly
Thin flakes are flexible but not elastic.
|Other ID Marks
Larger crystals and masses may have a slightly greasy feel.
Chamosite is more common then perceived, but it usually is just in small uninteresting flakes labelled as Chlorite without being specifically identified. Specific occurences include the Yaogangxian Mine, Hunan Province, China; Klenovec, Slovakia; Ashland, Middlesex Co., Massachusetts; Washington Pass, Okanogan Co., Washington; Atlantic City, Fremont Co., Wyoming; and Moat Mountain, Carroll County, New Hampshire. The New Jersey traprock quarries of Paterson and Prospect Park, Passaic Co., and the Milington Quarry, Somerset Co. contain Chamosite coatings and dustings upon other minerals.
Distingushing Similar Minerals
Muscovite and other micas - Are more elastic then Chlorites.
Talc - Softer (1).
Other Chlorite minerals - Indistinguishable by practical methods.