Extraction of three different phases of metapelites, mostly phyllites as the Carbonate phase, Fe-Mn Phase, and Silicate phase has been obtained. After doing ICPMS, different results have evolved. Since the phyllites are associated with Carbonates and Iron formations, phase extraction was carried out.
How those three phases can be distinguished and inferred for proper understanding?
Carbonate minerals are soluble in HCl and monochloracetic acid, many silicates (such as mica, feldspar, quartz...) are disolved by HF, others common to medium and high-grade metapelites , e.g., kyanite, and sillimanite are left unaffected. HF does not work in case of Fe-Mn-Cr oxides of the spinel s.s.s. and a couple of ultrastable HM such as zircon, tourmaline, and rutile or its "relative" ilmenite. Phyllites contain clay minerals of the chlorite s.s.s. which according to their Fe-Mg ratios are attackted by HCl, chloritoid which is not uncommon in some low-grade metapelites can be separated by this leaching due to its inert state.
Before extending this sequence of solubility you should list which minerals you encountered during thin section analysis or XRD investigations.
Harald G. Dill , Thank you for the information. but sir for the initial Carbonate separation, I used acetic acid, and to remove the Fe-Mn fraction I had used Hydroxylamine Hydrochloride. The rest leftover was silicates that were determined. I didn't do the separate XRD study but according to the bulk XRD analysis, I could find Quartz, muscovite/Biotite in almost all whereas Manganese minerals, kaolinite, and calcite are some of them.
How can you speculate on Fe- and Mn minerals ? Kaolinite is not an ordinary silicate of the low-grade stage metamorphic metapelites.
Then please suggest me the alternative. How can I proceed with those samples?
I performed the mineral separaration for geochronology and special mineral analyses. Whatever you make use of from jigging actions to flotation, a good mineralogical-petrographical investigation is a prerequisit. Thin section/polished section analyses or MLA is give priority to XRD, because of the detailed information about the granulometry and morphology that you can obtain from the first two methods in addition to the mineral association.
H.G.Dill
I cannot understand the question. What are you trying to do? Do you understand the difference between magnesium and manganese?
Brian P. J. Stevens, according to my question, with the help of different reagents, if we separate out three phases {Carbonate, Fe-Mn, Silicate} then how can we get to know about redox and depositional source signatures. I wanted to have an idea of how these would give a different interpretation than bulk sample digestion.
Yes, I do understand the difference between Mg and Mn. Since I expect my samples to be volcanogenic sedimentary rock, which could have higher Mn than Mg.
Dear Mr. Behera,
please put the cards on the table.
What did you do to determine your mineral assemblage?
How did you categorize your host sediments?
Why do you expect higher Mn contents than Mg contents? Mn is not a common element in this environment but present in anomalously high quantities only when ore-forming processes affected this mixed-type environment of sedimentary and pyroclastic/volcaniclastic rocks.
Therefore, the answers provided can only be highly speculative and end up in some poking around in the fog. Everybody is poised to help you but you have to deliver on your part, too.
H.G.Dill
Thank you Kamalesh. I assume when you refer to Fe-Mn, you are talking about Fe-Mn oxides, while the Mg (and some Fe) are in the silicates. As Harald G Dill says, you need to present more information before the appropriate advice can be given.
Below I have attached the XRF findings for those samples which made me curious about the Mn.
According to the field observation, a stretch of phyllite layers was observed in between dolomite and limestone formation which was hosted by banded hematite quartzite(BHQ). We could observe some Mn nodules as well as Mn clay near the junction of carbonates and phyllites.
Hope this helps Harald G. Dill, Brian P. J. Stevens
- Badges
- Science topic
- Similar topics
- Philosophy
- Esthetics
- Interpretation