rich Wrote:
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> Archae,
> I appreciate the dialog.
>
>Slide 21 shows more Magnesium 3.3-9.1% in the
>Lauer sample, vs. 0-.89% in the Tura Sample and
>the EA-491.

>Asbestos("Mg3(Si2O5)(OH)4") has a Mg-Silicate
>bond... and is used in cement. The Calcium would
>come from the lime.

There is no chrysotile in the XRF data for the insoluble residue; if it’s there it’s below the resolution of this method of testing which is less than 5% of the sample (i.e. insoluble residue, which would be less than 5% of that 3.3% SiO2 of the sample since that is all that is actually showing up in XRD (i.e. varieties of quartz)). There is only 1.18% MgO in the bulk chemical analysis of the Lauer sample. It’s not much mixed in with anything insoluble as a mineral. The rest of the Mg is in something soluble like dolomite. The SiO2 is concentrated in interstitial location through the porous limestone sample; it’s not ubiquitous to all the sedimentary grain boundaries in the Lauer sample. That less than 3.3% SiO2 in the bulk chemical analysis of the Lauer sample in not a primary cement. What are being tested in slide 21 are the spherical silica-rich lepispheres not fibrous grains of asbestos or a lepispheres contaminated with a low-grade metamorphic minerals. These appear to be somewhat amorphous silica aggregates (opal-A or something like that) contaminated with Mg as interstitial elements within the weak crystallographic structure. This can also be contaminated with Al as a substational element for Si, as well as with calcite. Thus the significantly higher % MgO values and lack of any Mg-silicate in the XRD data of the insoluble residue. The Mg% value is varying from one location to the next within the Lauer sample so it would be expected to also vary from one location to the next with in the Tura deposit. Where do you think the lepispheres in the Tura limestone came from and why are they also showing up in the Lauer and EA samples?

Archae Solenhofen (solenhofen@hotmail.com)