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Techniques for CollectorsLeaving partially etched calcite on specimens

26th Oct 2018 13:36 UTCBob Harman

Today, Oct 26 2018 I have been looking over the Munich Show pictures.

There is a Chanariello, Chile PROUSTITE specimen with, to my eyes, clearly partially acid etched calcite. In addition, also to my eyes, the remaining calcite does not seem necessary to preserve the integrity of this whole specimen. The remaining calcite seems both unnecessary and unaesthetic.

Any general comments regarding leaving obviously partially acid etched calcite on a specimen if the remaining calcite is unaesthetic and unnecessary to maintain the overall integrity of a specimen. CHEERS.....BOB

26th Oct 2018 14:23 UTCReiner Mielke Expert

From an aesthetic point of view I agree, if the calcite is not necessary then it should be removed. However from a scientific point of view the calcite is important to show the environment in which it was found and to preserve some of the calcite which may be geochemically unique .

26th Oct 2018 15:00 UTCEd Clopton 🌟 Expert

I agree with Reiner. The answer depends on whether it is to be primarily a display specimen or a study/reference specimen. The remnant calcite might (and might not) detract from the appearance, or it might provide useful information for scientific purposes. If some remains, it can be etched off later if desired for appearance. If it is removed entirely, it can't be restored later to answer questions about its paragenesis.

29th Oct 2018 06:58 UTCDale Foster Manager

I also disagree, but I do not consider the calcite to affect the aesthetics of the specimen, also based upon the photograph how do we know it isn't structurally important to the specimen.

I personally think that minerals that are totally free from their host matrix are less interesting and lose their context.

Now there are some examples that are pretty much inevitably free of matrix e.g. the pseudomorphs of Cassiterite after Feldspar from Wheal Coates, but just seeing isolated crystals without matrix is generally less interesting for me.

29th Oct 2018 09:20 UTCRuss Rizzo Expert

Consider this; completely removing the calcite from the specimen with acid would damage the proustite. Removal of calcite from the proustite by mechanical means is also not an option as proustite is too soft. The calcite that was on the specimen prior to removal was most likely damaged/aesthetically challenged. Hence the careful employment of acid to dissolve the calcite in order to improve the specimen's aesthetics.

4 edits, a new record for me.

note to self: don't post to messages when over-tired...

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