Document 9J40LrOkOz5bmE79yVx4pweg3

FILE NAME: RT Vanderbilt (RTV) DATE: 1983 Mar 8 DOC#: RTV088 DOCUMENT DESCRIPTION: Letter from Univ of Maryland to Guy Driver RE Case of Poindexter vs. R.T. Vanderbilt DEPARTMENT O F G4E5O4*L3O5G48Y ' c r U N I V E R S I T Y O F M A R Y L A N D DIVISION OF AGRICULTURE AND UFE SCIENCES. COLLEGE PARK 20742 J )a ic/' if, /)d'l /fi? Hr. Guy Driver P .0 . Box 81 Winston Salem, North Carolina 27102 Dear Mr. Driver; With a view toward t e s tify in g in the case o f Poindexter vs R. T .V a n d e r b ilt, . . 1 have examined two samples labeled Nytal 300 and Nytal 400 which were sent to me ' by Mr. A1 Harvey. The methods 1 used to examine these samples are polarized ligh t microscopy, Becke lin e technique and dispersion sta in in g . I have identified the following minerals in these samples; platy t a l c , trem o iite , fibrous ta lc and anthophyllite. Of th ese, trem oiite and a n th op h yllite can occur in nature in an asbestiform habit and are then c a lle d asbestos. The c h a r a c te r is tic s o f th is habit which are v is ib le using the optical microscope are: . 1. fib e r bundles e x h ib itin g splayed ends 2. P a ra lle l e x tin c tio n , a c h a r a c te r is tic o f asbestos only when the ordinary v a rie tie s ex h ib it oblique extin ctio n such as for trem oiite 3. curved fibers b . extreme elongation, often in excess o f 100:1 The trem oiite and an th op h ylIite present as major constituents o f these samples do not exh ib it any o f these c h a r a c te r is tic s . A ll of the trem oiite arid anthophyl1Ite p a rtic le s I observed are properly calle d cleavage fragments. Most of these cleavage fragments are elongated and many have aspect ratios in excess o f 3:1 Rarely, p a rtic le s with aspect ratio s o f up to 20:1 were observed. According to our e x istin g federal government regulations these cleavage fragments can be called fib e rs o f asbestos. However, th is is not m ineralogicaliy v a lid . I observed no anthophyl1Ite or trem oiite asbestos fib e rs In the samples I examined. There are, however, true mineral fib e rs in the samples. I have Identified them as fibrous t a l c , --They are distinguished from the amphibo.les trem oiite and anthophylIite refraction of on the basis fibrous ta lc of their does not einxdceeexdo 1f .6r0e0frafocrtioAn.. =>T5hSe$nmmax. imAulmmoIsnt daexl l of o f the fib ers i observed in these samples had indices of refraction less than 1,600. This value is much too low fo r trem oiite or anthophyliite asbestos. Fibrous ta lc is thought to form from anth op h yllite and/or trem oiite . It also exh ibits the c h a r a c te r ls tes U sted above for the asbestiform h ab it, in the samples I examined, there were a few fib e r s which f a ll somewhere between anthophyliite-asbestos and fibrous t a l c . The abundance o f th is intermediate material Is vanishingly small and occurs in trace q u an tities only (^0.01% ). RECEIVED HAS 10 3f3 Sincerely yoursv Q ""' Ann G. Wylle Associate Professor i *' WES000838