Please find attached two of our papers dealing with emerald formation during regional metamorphism in metasomatically altered metapelites, forming emerald-bearing blackwall zones between metapelites and serpentinites, in Habachtal, Austria.

Kind regards

Guenter Grundmann

Dear Silas Samuel

Read the attach paper below

Dear Mr. Dos Santos Costa,

You can use almost all stratabound and/or stratiform mineral deposits older than Mesozoic to get an idea about the response of mineralogy and chemistry of mineral deposits in pelites to metamorphic overprinting. Orogenic processes along with P and T increases gave rise to metamorphic regimes of at least very low grade stage. While under these metamorphic conditions you will be able to distinguish sedimentary features such as bedding, marks, grain size etc. with increasing physical-chemical metamorphic conditions these primary characteristic will gradually get overprinted by dynamo-metamorphic and regional metamorphic processes which eventually lead to the creation of metamorphic felsic mobilizates.

To get swiftly acquainted with these sedimentary and metamorphic petrological conditions in various environments of deposition I give you a piece of advice to read the comprehensive overview given in

DILL, H.G. (2010) The “chessboard” classification scheme of mineral deposits: Mineralogy and geology from aluminum to zirconium. - Earth Science Reviews, 100: 1-420.

All mineral assemblages being enriched from Al to Zr up to ore grade are categorized as follows:

1. Magmatic

2. Structurebound

3. Sedimentary

4. Metamorphic

Select part 3. and 4.and see which of them have shales, slates, phyllites, mica schists or paragneisses as host rocks and you will be able to make comparisons among pelite-hosted mineral deposits in very low-grade conditions and those undergoing a more advanced level of metamorphic overprinting.

Further literature is cited there and hints are given to various basic studies.

I wish you much success.

Harald G. Dill