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Amphibole group: programme for classifying microprobe or wet chemical analysis

Posted by Uwe Kolitsch  
Uwe Kolitsch October 15, 2011 06:21PM
Esawi, E.K. (2011): Calculations of amphibole chemical parameters and implementation of the 2004 recommendations of the IMA classification and nomenclature of amphiboles. Journal of Mineralogical and Petrological Sciences 106, 123-129.

The amphibole group is a complex, compositionally diverse group among silicates, and exists in large varieties of rock types and P-T ranges making it very useful P-T and petrogenetic indicator. In 2004 the International Mineralogical Association (IMA) revised its 1997 nomenclature scheme for amphiboles to accommodate all known amphibole species including several species discovered after 1997. The main difference between the 1997 and 2004 schemes is that amphiboles were divided into five groups in the 2004 scheme instead of four groups in the 1997 scheme. ClassAmp is an MS Excel-VBA program that implements the 2004 IMA revisions of and additions to the 1997 nomenclature scheme of amphiboles. In addition to implementing the new nomenclature scheme of amphiboles, ClassAmp is flexible where it can be used to classify microprobe or wet chemical analysis; obtain any combination of amphibole's cation names, cation values, structural formula names, structural formula values, groups, names, prefixes, and modifiers; properly format chemical symbols, associated with amphibole nomenclature so that the output can be directly imported to final drafts/publications; and determine pressure-temperature involves amphiboles as well as other petrogenetic determinations.
Frank K. Mazdab October 15, 2011 08:27PM
I was a reviewer for an earlier version of this manuscript several years ago and couldn't get the program to work on my computer, despite repeated consultation with the author. It was ultimately not published then. I notice in the current version of the paper the author specifically notes the program is unlikely to work on Macs, which may have been the problem I had in the past. I personally still believe that with the Leake classification in hand, and with only a minimal understanding of writing formulas in Excel, a program such as this is not really necessary. It is a fairly straightforward exercise to input formulas into Excel to classify and name amphiboles (or any other mineral groups) oneself, and it is a great learning experience for students. The hand-written set of formulas I use, which took only a few hours to set up, even checks for the optional chemical modifiers (e.g. "potassian", "chlorian", etc.) and includes them with the name, where appropriate.
Olav Revheim October 16, 2011 08:51AM
I have downloaded the excel spreadsheet, and I think it is absolutely great for my use. When downloading, just remember to activate macros. I hope that someone will take the time and effort to develop something similar for the micas, tourmalines and other complex groups.

Thank you for posting Uwe.


Edited 1 time(s). Last edit at 10/16/2011 08:54AM by Olav Revheim.
EK Esawi April 19, 2012 07:56PM
I must state at the outset that I am the author of the program. Let me say that I respectfully, sincerely, and strongly disagreed with your assessment then and now. I remember our correspondence; I am sure I had stated that the program may not work on MAC simply because Microsoft stated that it may not provide VBA support for MAC. You are not the only MAC user who did not like my program; another MAC user did not like it for the exact same reasons when submitted to another journal. Yet, none had problems using the program or mentioned any problems with it despite the fact that it’s been use a lot.
In my view the problem is not with the program but with MAC users for many reasons that we all know. More importantly, I will challenge anyone who could write an efficient formulas, etc. that can be used to classify any given amphibole unless one uses the whole sheet for one analysis-try that for 800 analyses. I had seen many of such formulas, macros, etc. but they are very inefficient and very time consuming. My program works well and very well tested
Frank K. Mazdab May 04, 2012 04:08AM
While I appreciate the effort you put into developing your program, and I applaud the rationale behind it, I think you're giving yourself way too much credit for your accomplishment. The fact of the matter is that an amphibole nomenclature routine (or for that matter, a nomenclature routine for any mineral group) can be easily put together in Excel without the need for VBA programming, simply by using the formulas already available in Excel. Indeed, one of the assignments I've given to my mineralogy students (both graduate and undergraduate) is to derive an Excel-based spreadsheet which normalizes EPMA amphibole analyses, and I give further "brownie points" if they include a nomenclature routine.

Amphibole nomenclature is based on simple chemical rules, outlined in Leake et al. 1997 and Leake et al. 2004. For example, if an amphibole has Ca >= 1.5 apfu in the M4 site, Na+K >= 0.5 apfu in the A site, Ti < 0.5 apfu, Si > 6.5 apfu in the T site, and Mg/(Mg+Fe2) > 0.5, then the mineral is edenite. In this example, 5 chemical parameters define edenite, and these 5 parameters can be easily incorporated into a set of nested IF statements in Excel. In older versions of Excel (which I still use), one is limited to no more than 7 nested IF statements. So, to name all the amphiboles takes me 25 columns of nested IF formulas, and that number of columns seems somewhat high because most of my columns contain considerably less than 7 nested IF statements, just to limit the complexity of any individual formula and keep things organized and attractive. Newer versions of Excel dispense with the nesting limitation, and thus the formulas could be reduced to very few columns (albeit individually more complex).

Not only do I name the basic amphiboles, but I also include extra columns which test for the presence of minor elements in sufficient quantity to be included as obligatory modifiers (i.e. if K > 0.5 in the previous edenite example, the name would be potassic-edenite). Similarly, I include columns for the optional chemical modifier, so for example I might end up with a name such as chlorian potassic-edenite.

Contrary to your assertion that such formulas would require a whole sheet per analysis, my all takes place on one line. So it is easy to input an amphibole chemical analysis on the left-hand side of the spreadsheet, copy the formulas down from the preceding line, and instantaneously name dozens or hundreds of entries. My spreadsheet not only allows for an assigned (or floating) Fe3/∑Fe ratio, but also for an assigned (or floating) Mn3/∑Mn ratio, to permit normalization and naming of amphiboles such as kornite and ungarettiite (with an optional input for Li estimate for the former). The amphibole normalization section allows for 6 different "normal" cation-based routines, 2 different routines optimized for Mn3-bearing amphiboles, and the traditional 23 O routine. If one routine doesn't work well, simply changing a few cells makes another routine available.

In addition to amphibole, I've set up comparable sheets for pyroxenes, the eudialyte group, micas, tourmalines (the most difficult one), the osumilite group, the epidote group, and several other complex mineral groups. Each spreadsheet took me about a day to put together, with the original amphibole one taking the longest and the other ones loosely modeled after it.

All in all, it's a great exercise to have complete control over how minerals are normalized and named. There are no "black box" formulas someone else wrote to rely on. And because it's written using the standard Excel formulas, it works in all versions of the program, across all computer platforms, Mac & PC included. To be clear, it's not my intention here to offer a nomenclature program to compete with yours. My point is simply that while a program such as yours certainly has its value, I would personally recommend to anyone interested in normalizing chemical data and naming minerals to simply sit down with Excel, with the appropriate issue of Canadian Mineralogist or European Journal of Mineralogy (these two journals seem to have the most collected nomenclature papers), and a free afternoon, and just build a spreadsheet to suit your own needs.
Stuart Mills May 04, 2012 08:18AM
Based on the new amphibole nomecnlature which has recently been approved Roberta Oberti will be offering some spreasheets via her institutions website.
Jolyon & Katya Ralph May 04, 2012 09:42AM
I hope that those producing spreadsheets in Excel will also check they work in OpenOffice as well - they should if the formula code is simple enough.

Not everyone has Excel these days!

Ralph Bottrill May 04, 2012 10:16AM
I find the most complicated part is estimating the Fe2+/Fe3+ which is vital to calculate the formulae.

Uwe Kolitsch May 04, 2012 05:36PM
Coincidentally, there is a new paper on this issue:

Determination of Fe3+/Fe using the electron microprobe: A calibration for amphiboles
William M. Lamb, Renald Guillemette, Robert K. Popp, Steven J. Fritz, and Gregory J. Chmiel
American Mineralogist 2012;97 951-961
Ralph Bottrill May 06, 2012 04:41AM
Thanks Uwe, I look forward to that paper

EK Esawi July 12, 2012 02:17PM
First of all let say that when I replied to this forum and in particular to Frank’s comment. I neither intended nor it even crossed my mind that I am giving myself any credit. I simply stated some facts that are valid now and when I wrote and submitted my paper; chief among them is that no other user or reviewer has ever found any problems with the program, as far as I know.
I still think that it’s nearly impossible to use Excel formulas alone in an elegant and comprehensive way for the nomenclature of most minerals, let alone amphibole, mica, etc. You stated you used 25 columns of nested IF statements and that’s where the problem lies in my view because: (1) nested IF statements, with or without arrays, are clumsy inefficient and difficult to edit and modify; (2) using nested statements, you need the whole sheet just to classify amphiboles and you will have to copy the results somewhere else, (3) I am wondering if such a big set of nested statement can be extensively tested and if it can be used for any type of amphibole analysis; and (4) I think it takes far more than an afternoon-at least it took me far more-to do anything that complicated.
In any case, I leave it to users to judge for themselves. My program has been used a lot and just yesterday, someone from Germany requested a copy.
PS. Anyone knows when the newest amphibole classification comes out. I was told many times that I will in so and so and never do.
EK Esawi February 22, 2013 12:48AM
Hi All--Anyone tried the 2012 amphibole program. It can be downloaded from the IMA site and was listed on the original article. I tried to download it to 2 computers but I id not run on either and there is no documentation files at all. EK Esawi
Olav Revheim February 22, 2013 06:47AM

It works fine for me. I had some error messages when downloading it also. If I remember correctly it still should work OK. My biggest issue was to find out how I changed the comma separator from , to .

Roberta Oberti February 22, 2013 10:48AM
Dear all,
should you have problems in downloading the program based on the 2012 scheme for amphibole classificatiion and nomenclature, please contact me ( I will send it as a .zip file. Unfortunately, it is bigger than 1MB, and I cannot attach it to this message.
Hence, I am attaching only the paper published on the Periodico di Mineralogia.
open | download - Oberti et al how to name PM2012.pdf (289.9 KB)
EK Esawi March 04, 2013 03:23AM
Hi Olav,

I have a copy of the program too and it works for the example with the program. However I have problems figuring out how it works with data files, the format of such files, etc.

I am planning on updating my previous program to accommodate IMA12. This is basically because I believe Excel is an overall better suited for such calculations and the fact that one still has to calculate the structural formula and readjust the ferric/ferrous ratio-a simple task but very clumsy to do via formulas in Excel, convert to text files, etc.
Thanks, EK Esawi
Roberta Oberti April 08, 2013 10:51AM
For those who are interested in amphiboles.

A new and implemented version of the program AMPH 2012, which gives the correct name to amphibole compositions after the IMA report (Hawthorne et al. American Mineralogist, 97, 2031-2048,l 2012) can now be downloaded at

This 2.0 version also covers orthorhombic amphiboles and acknowledges the recent recognition of the new rootnames ghoseite (for rootname 11) and suenoite (for the orthorhombic counterpart of rootname 3).

Mistakes in the use of the magnesio- prefix have been corrected.

Multiple entries from a file are now allowed.

Should you need any help or further explanation, or should you find any mistake in the procedure, please do not hesitate to contact me. Your feedback has proven to be very useful.

All the best

Roberta Oberti
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