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Field determination of the dolomite % of chip samples http://www.epgeology.com/general-geology-rock-identification-f49/field-determination-the-dolomite-chip-samples-t2591.html |
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Author: | rcarrgeo [ Fri Jul 20, 2012 5:07 am ] |
Post subject: | Field determination of the dolomite % of chip samples |
Does anyone have any tips on determining dolomite percentage in a well-site setting? I was thinking that comparing the rate of effervescence in a 10% HCl in water solution could give some quantitative results. Maybe comparing the rate while changing parameters such as temperature of solution, strength of HCl solution or powdered vs solid sample. I could make a chart with the rate of known samples under these different conditions to compare to. I haven't tried this yet but what do you think? Any tips or better ideas? Thanks! To be clear I mean % dolomite in limestone/dolomite samples |
Author: | Darryl [ Wed Jul 25, 2012 11:19 pm ] |
Post subject: | Re: Field determination of the dolomite % of chip samples |
Have you tried staining with Alizarin Red and estimating the % of rock that turns red? The dolomite won't stain. If there are other minerals in your sample they may or may not stain but this is pretty much the standard mud loggers test. Page 37 of Well-Site Geologist's Handbook by Donald McPhater and Brian MacTiernan, published byPennWell Publishing Co of Tulsa Oklahoma 1983 has a table that lists the colors various carbonates stain using a solution of 0.2% HC, 0.2% Alizarin Red and 0.5% Sataurated Potassium Ferricyanide. But I just use a commercially available solution (concentration unknown - not on lable) of Alizarin Red and get pretty much the same results. Roughly speaking the table is as follows: RED - pure calcite Mauve - Ferroan Calcite Fe oxidation state +2 poor purple - Ferroan Calcite Fe oxidation state +2 rich Light Blue - Ferroan Dolomite Dark Blue - Ankerite Unstained - pure dolomite Good Luck! |
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