Cross-fiber asbestos

Cross-fiber asbestos Term applied to aggregates of asbestos in veins (see Fig. 1.1 A) in which the fibers are arranged in parallel position, usually perpendicular to or sometimes at a low inclination angle to the rock surfaces. The term may be applied to either serpentine- or amphibole-asbestos. 

Tiger s eye is a yellow and brown-banded gemstone, and Hawk s eye is similar but with blue bands. Both come from South Africa and result from silicification of cross-fiber veins of crocidolite. Cut en cabachon, and parallel to the fiber length. Tiger s eye and Hawk s eye exhibit variations in sheen and color that arise from the not-quite-parallel arrangement of the intimately associated asbestos and quartz. 

Measurement of the angle of extinction can be performed as follows Line up the cross hairs (if the eyepiece does not have a cross hair, it is possible to use the lines of a Patterson Globe and Circle Reticle or a porton Reticle) with a natrolite particle or fibers of an anthophyllite asbestos standard which is at extinc... 

The optical behavior of asbestos fibers viewed with crossed polars has been described. Crystalline fibers have positions of extinction 90° apart. The fact that crystalline fibers have retardation has also been mentioned. With crossed polars and a first order red plate in place, asbestos fibers will go from yellow to extinction to blue, back to yellow, etc., upon rotation of the stage. If the fiber bends, this is equivalent to a rotation of the stage and the color will change. If the fiber... 

Plant fibers are usually much thicker than asbestos fibers, the ends of branching fibrils are stubby, internal structure can be seen with crossed polars. 

The fibers will have a circular cross section and the ends will break in characteristic ways. Bundles resembling asbestos bundles will not be seen. 

Example 1.3 An asbestos fiber is 10 ixm in length with a circular cross-section of 0.5-(jun diameter. Find the diameter of a sphere that has the same volume as the fiber. 

Microscope slides (72 mm x 25 mm x 0.8 mm approximately) and coverslips should be of the best optical quality and of the correct thickness for obtaining quality images (usually 0.17 mm). In the case of counting a particular fiber, an assumption has to be made about the cross-sectional profile of the fiber type chrysotile is usually assumed to be cylindrical in shape, while the amphiboles are considered to have a thickness-to-width ratio of 1.6 1. Discrimination of asbestos fibers using the morphology and refractive index in such cases is aided by prior identification of the fiber types present in the bulk material using PLM or other methods. 

The gelation process does not work well to produce special-shaped filaments the dogbone cross-section is not suitable as a carbon fiber precursor and it is not possible to produce a fibrillated product for the asbestos-replacement market. 

Whereas fibers of chrysotile resemble rolls of newspapers when viewed as a cross section of fibers, crocidolite is an amphibole and its fibers are laves with a trapezoidal cross section. As mentioned, this behavior is related to the cross-linked double chains of silicate from which these fibers are formed. Like [NaCa(P03)3]n which is grown as single crystals and must be milled to be converted to fibers, crocidolite is not a natural fiber as it is mined. It must be milled before it is cleaved to fibers. Unmilled crocidolite mineral is a beautiful stone known as either Cat s eye or Tiger s eye. It is also known as Riebeckite Asbestos. ... 

Textiles can be made from many materials. They are classified on the basis of their component fibers into, animal (wool, silk), plant (cotton, flax, jute), mineral (asbestos, glass fiber), and synthetic (nylon, polyester, acrylic). They are also classified as to their structure or weave, according to the manner in which warp and weft cross each other in the loom. Textiles are made in various strengths and degrees of durability, from the finest gossamer to the sturdiest canvas. The relative thickness of fibers in... 

Fig. 22. Volume resistivity versus time of electrification. A, Cross-linked PE, 23°C B, cross-linked PE 100°C C, dry PVC D, wet PVC and E, asbestos fiber-filled epoxy resin.

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