MINAL3

MINAL – a program for efficient work with chemical analyses of minerals

MINAL (version 3) is a handy ©MS Windows-program, mostly oriented on ordinary work with arrays of chemical analyses of various minerals. The main features of the program that distinguish it from simple formula calculators:

• The format of the data files is a simple text table with a rowwise arrangement of analyses and a tabulation character as a column separator, with arbitrary order of the columns. This format is convenient both for reading and editing in simple text editors, and when working with MS Excel (and similar programs) through copy and paste operations. In addition, the program has a customizable export of data to applications created in the ©MS Excel environment for working with individual groups of minerals and solving other tasks.
  
• One table may contain analyses of different minerals: the program determines the required calculation method for each analysis by the abbreviation (or full name) of the mineral in one of the columns.
  
• Two basic modes of formula coefficients calculation are implemented in the program. The first of them – "by charges", where the normalizing factor (divisor) is the ratio of the sum of charges obtained by measured atomic quantities of elements with positive oxidation states to the sum of charges of the anionic part of the theoretical formula of the mineral, taken with a positive sign. Most often, this mode is numerically similar to the oxygen method. The second mode is called "by atoms" for the generalization purpose, it assumes a strict correspondence of elemental contents to stoichiometric ratios in the theoretical formula of the mineral. Its normalizing factor is the ratio of the sum of the measured atomic quantities of elements to the sum of atoms for these elements in the basis – a selected fixed part of the mineral theoretical formula. In most cases, the basis is the whole mineral formula or its cationic part. However, often only a part of the formula is chosen as a basis. For example, calcium amphiboles are typically calculated for 13 cations in a basis set of 8 tetrahedral and 5 octahedral positions that do not contain alkali metals and calcium (these elements are excluded from the basis set, respectively). For most minerals belonging to oxygen compounds and halides, both modes are applicable (with one of them being preferred), their input data are presented predominantly in the form of wt. % oxides. For sulfides and their analogs, as well as intermetallides, the charges mode is not used in most cases, and the initial data are presented in wt. % of elements. It is possible to hide analyses based on the applicability of the charge mode for convenience (reducing the displayed columns of the polymineral table).
  
• The calculation of formula coefficients can take into account a number of additional parameters required for correct work with individual minerals:
  • Declaring some elements with positive oxidation states as being part of anionic radicals (e.g. hydrogen or sulfur) – these elements are not taken into account when calculating the sums of charges and cations.
    
  • Correction of the sum of charges for elements participating in heterovalent substitutions with a change in the charge of the anionic part of the formula. For example, the incorporation of Ti⁴⁺ into the octahedral positions of biotites and amphiboles is most often associated with so-called "oxo-titanium" substitution according to the scheme M²⁺ + 2OH^- → Ti⁴⁺ + 2O^2-, in which the sum of charges (for which the formula should be calculated) increases proportionally.
    
  • Correction of the sum of cations for elements, the presence of which leads to the appearance of vacancies or the replacement of cations by anionic groups. For example, in hydrogarnets, the appearance of fluorine and hydrogen (in the form of O₄H₄ groups substituting for SiO₄ tetrahedra) requires not only correction of the charges in the anionic part, but also a proportional reduction in the sum of cations for which the formula should be calculated.
    
  • Charge balancing using elements with different oxidation states (most often Fe²⁺/Fe³⁺ and Mn²⁺/Mn³⁺).
    
  • Forced reduction of the formula to a charge-balanced variant. For example, when calculating formula of andradite "by atoms" with measured FeO_tot, a positive charge disbalance still remains after balancing Fe²⁺/Fe³⁺, then the contents of all elements are proportionally increased to its zero value.
• Microprobe analyses can be linked to backscattered electron images, and any information from the table can be displayed next to the points, which helps in the analysis of mineral relationships.
  
• The program implements data import from ©JEOL JED Series Analysis Station and INCA Suite software (by ©Oxford Instruments) for the most popular type of microprobe examination: single point sampling. Electron microscopic images with points attached to them are also imported. For individual analyses it is also possible to import statistical errors of element and oxide determinations.
  
• The program contains a tool for reverse calculation of wt% of oxides/elements from formula coefficients (both copied from the table and entered manually or loaded from a file) with the possibility of copying the results to the working table.
  
• Conversion of wt. % of one oxide into other oxides with a different oxidation state of the element. It is possible to enter additional data on the ratios of elements with different oxidation states (e.g., based on Mössbauer spectroscopy results).
  
• Calculation of mineral-dependent user-defined coefficients using mathematical expressions and logical constructs. This tool is used, in particular, to calculate structural formulae (with distribution of elements on different sites) and mole fractions or proportions of components (minals) and values for diagrams. This functionality has been added recently, so there are not many files with coefficient sets yet.
  
• Plotting mineral-specific diagrams, with the ability to add your own variants and to edit existing ones. To work with diagrams, another author's program is required – TriQuick, which is an editor and server of diagram graphics. Diagrams have also been added to the program recently, so their set is very limited yet.
  

The program is freeware and distributed as a zip archive: to install it, all you need to do is extract the directory with all its files from the archive to any location on your hard drive or other media.

MINAL (version 3) has a long history of development and use in a limited group of users. After the addition of new functionality, which significantly expanded the capabilities of the program, it was decided to make it publicly available. The development of the program is not complete, and changes and new features are periodically added (accompanied by the almost inevitable emergence of new bugs, which the author tries to fix promptly). MINAL informs users about new versions using a built-in checkout mechanism. However, data files containing custom coefficients and diagrams for various minerals are added and modified without notice.

Of course, when publishing results calculated in MINAL (as in other similar programs), it is always necessary to report all the important calculation parameters like corrections for sums of charges and atoms.

NB! Some time has passed since the recording of the videos below, new features have appeared, so some elements of the program interface have changed since then!

Basics of working in MINAL v.3.1:

Import from the ©Oxford Instruments INCA Suite program:

Import from the ©JEOL JED Series Analysis Station program:

Working with custom coefficients:

Bibliographic reference:
Dolivo-Dobrovolsky D.V. MINAL – a program for efficient work with chemical analyses of minerals // Proceedings of the Russian Mineralogical Society, 2025, No. 1, pp. 131-137. DOI:10.31857/S08696055250108e6, EDN: FTGCXZ

NB! DOI link is not working yet!