Document bBJ82DgbZvKkdvLRmp9by2eey

^-- TO: H. A. Brown FROM: H. C. Duecker CC: R. M. Vining cambridg: vGmwmm Deceived 1exhibit jtA-12 JUinm t*Rrra.oi ftc6jVs e,*^ DATE: S$573 SUBJECT: Asbestos in Vermiculite and M0N0-K0TE& Ref: Yang's 6/26/73 memo. Brown's 7/10/73 memo Normally, the analyses of tremolite in MDNO-KQTE and vermiculite are given only by ore sources. Yang's memo of June 26, 1973 was a compilation of data to be submitted to the EPA with the intention of showing that M0N0-K0TE contained no more than trace quantities of tremolite. To be accurate, all analyses had to be considered. The picture regarding the relative tremolite contents of Enoree and Libby vermiculite is not clear to us at this time and the data were purposely presented as they were in view of the following facts: 1. Using our x-ray diffraction technique, tremolite has thus far been detected only in M0N0-K0TE made with Enoree vermiculite. No tremolite has been detected in any analysis of M0N0-K0TE made with Libby vermiculite.(Correction: 1 sample with tremolite.) 2. Microscopic examination of the Enoree M0N0-K0TE samples which contain tremolite shows that at least some of this tremolite is present in the fiber form. 3. Uc have not yet developed e technique for determining the rstio of platy to fibrous tremolite within a sample of M0N0-K0TE or vermiculite, and therefore cannot make further statements in scientific confidence. It is our opinion that: a. The platy tremolite of the Enoree deposit is higher than the platy content of the Libby deposit. b. Platy tremolite is more difficult to separate from platy ver miculite (in the milling process) than is fibrous tremolite. c. The platy tremolite has some tendency to fragment upon expan sion, giving some tremolite falling within the fibrous defini tion. However, we believe that the majority of the tremolite remains in the platy form. In conclusion, it is our opinion that Libby and Enoree M0N0-K0TE may contain trace amounts of fibrous tremolite at concentrations less than the limit of detection using the x-ray diffraction technique. Enoree M0N0-K0TE may also contain platy tremolite. The average content of the total tremolite in MDNO-KOTE is about 0.2-0.5$. (Due to the inhomogenity of the product and day to day variation, individual samples may give higher values, but an entire bag of M0N0-K0TE probably never contains more than 0.2-0.5# total tremolite.) HCD:mlr H. C. Duecker