PALYGORSKITE
Specimen pal-4

Dims: 3.3" x 2.4" x 1.0" (8.4 x 6.1 x 2.5 cm)

Wt: 2.04 oz. (58.0 g)

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

This specimen consists of a "host rock" that really cannot be called a "rock". The material in question is called Palygorskite, and it is in the form of extremely fine, fibrous crystals that are concentrated and intergrown into a matte that almost resembles a very fine cloth. Its color varies from a moderate gray to white, and it is opaque. The matte shows a dull sheen that actually makes me think of spiderwebs! This matte holds several individual crystals and clusters of Calcite together; those crystals that are exposed show excellent trigonal tabular "nail-head" form. They have well-defined edges and clean faces that show a pearly luster. All are colorless, transparent, and quite clear, though a few have visible inclusions. There is no other material present on the specimen besides these two minerals.

Dims: 3.4" x 3.3" x 2.0" (8.6 x 8.4 x 5.1 cm)

Wt: 4.56 oz. (129.5 g)

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

This particular Palygorskite specimen is quite rigid due to the large number of calcite crystals present and the high degree of their intergrowth. It does have a lot of Palygorskite on it, however, and there are a few floppy "tendrils" sticking off of the main mass. The Palygorskite occurs in the form of a fine matting of fibrous crystals, and has a color that ranges from white to dark gray. I suppose that its luster could be defined as "silky" to all intents and purposes, but it is not a high luster in any case. It certainly shows no semblance of crystal form. The associated calcites have an almost tabular, "nailhead" form, which basically consists of two very shallow, trigonal pyramidal terminations that are placed back-to-back. They are colorless and slightly cloudy, and show a pearly luster and dim translucence. A few of the larger calcite crystals are damaged, but most are in excellent condition. By holding the specimen and gently shaking it, one can see where the flexible protrusions are, as they will sway back and forth.

Dims: 6.1 x 1.0 x 1.0" (15.5 x 2.5 x 2.5 cm)

Wt: 8.3 g

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

This very odd specimen consists of a formation of Palygorskite, a mineral that is sometimes referred to as Mountain Leather. The mineral fits this nickname because it consists of long, microscopically-thin, flexible crystals that are matted together to form almost a "cloth". Thus, it is impossible to assess damage to this material and study its crystal form without very high magnification. The Palygorskite ranges in color from white to dark gray and is stiff at its base, but separates into tendrils, most of which are flexible. Attached to this "cloth" are many tiny barites that have good orthrhombic form, a rich brown color and excellent clarity. There is no host rock present, however.

Dims: 5.1 x 3.7 x 1.0" (13.0 x 9.4 x 2.5 cm)

Wt: 1.27 oz. (36.1 g)

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

A rather thick "cloth" of matted and interwoven Palygorskite fibers makes up this hand specimen. These fibers are so fine that one would need a powerful microscope to study them as individuals, but when matted together they possess an uneven gray coloration and a dull luster. There are several loose bits of the "cloth" that move easily due to the flexible nature of the fibers, and the Palygorskite serves as a base for several clusters and many tiny, loose barite crystals. These barites have good orthorhombic prismatic form and a rich brown coloration. They are transparent and moderately to very clear, and possess a pearly luster. Care shoud be taken when handling this specimen, as portions of it appear to be rather delicate.

Dims: 3.2 x 2.0 x 0.7" (8.1 x 5.1 x 1.7 cm)

Wt: 18.4 g

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

This small hand specimen consists of a few small clusters of tabular "nailhead" calcites that are held together by a fabric of Palygorskite, which is sometimes referred to as mountain leather. The Palygorskite has no visible crystal form- its crystals are so thin and fine that they are flexible and can be "matted" into almost a fabric. It is a bright white in color and dull and leathery in luster. The associated calcites are well-formed, colorless and dimly transparent, and have a dull pearly luster.

Dims: 3.5 x 1.7 x 1.7" (8.8 x 4.3 x 4.2 cm)

Wt: 3.16 oz. (89.6 g)

Pend Oreille Mine, Metaline Falls, Washington, U.S.A.

Several shreds of Palygorskite are partly embedded in the crystalline calcite of this specimen. These shreds are made up of countless superfine Palygorskite fibers that have been matted into a "fabric" of sorts. It has a pure white coloration and an almost silky luster and is quite flexible where loose. The surrounding calcites have an excellent tabular "nailhead" form and are rather heavily intergrown. They are colorless and dimly transparent and show a pearly luster.