New
To create a new standard composition simply click the Standard | New menu. From the Standard Composition window enter each element and it's concentration by clicking on a blank element grid row. To change a previously entered element concentration or cation ratio for oxide entered or displayed standards, simply click an already existing element row.
The program will automatically specify a default standard number based on the next free standard number starting at 1.
If may be desirable to group the standards numbers using some sort of a numbering system. In this case it will be necessary to change the suggested standard number. Generally some thought should be given to arranging the various standards together into functional groups. For example, it might be helpful to reserve standard numbers 1 - 106 for the elemental metal standards based on atomic number. Or perhaps to reserve standard numbers 200 - 500 for silicate standards only.
Note that if an already existing standard number is entered, the program will prompt whether the existing standard should be overwritten. If not, select another standard number. Note also that standard numbers between 1 and 2000 should normally be used to avoid conflicts or confusion with the standard numbers in the DHZ.DAT, SRM.DAT and ORE.DAT files.
Also enter the standard name and optionally a description or comment field to indicate the standard source or other pedigree information.
If the standard is a simple compound, it may be easier to enter the composition as a formula string. Click the Enter Atom Formula Composition to enter the formula string, for example fayalite entered as fe2sio4. To enter a formula string note that the parser is able to handle multiple occurrences of an element and even the use of parentheses. For example: "ca2mg5si8o22(oh)2"
All standard compositions are saved to the standard database as elemental concentrations, therefore, be sure to enter the oxygen concentration if oxygen is present in the compound. This applies to all standards, even those which are entered and/or displayed as oxide concentrations. To facilitate the data entry for the oxygen concentration of standard compositions which are entered as oxide concentrations, the program will display the calculated oxygen of the cations entered thus far. Therefore, if oxygen is entered as the last element in the standard, it is a simple matter to specify the displayed oxygen concentration from the calculated oxygen of the cations.
Be sure to also enter excess oxygen (for example minerals that contain ferric iron), into the standard composition since the presence of the excess oxygen will affect the overall calculation of the standard k-factors and mean atomic number.
For example, to enter hematite (Fe2O3) as a composition, one must enter two atoms of Fe and three atoms of O. Using elemental weight percent entry, enter 69.94 wt. % Fe and 30.06 wt. % O. Using the default oxide entry, of Fe expressed as FeO and elemental O, that would be two molecules of FeO and one molecule of O, or 89.98 wt. % FeO and 10.02 wt. % O (the excess oxygen). However, if the cations for Fe are changed to two atoms of Fe and three atoms of oxygen, then one can input the composition as oxide simply by entering 100% Fe2O3.
Note that "oxide" displayed standards that contain fluorine and/or chlorine will sum greater than 100 %, since these halogens actually replace some of the oxygen that is already being included in the oxide formulas of the other cations. The oxygen equivalent that is being included in the composition is usually small and can generally be ignored. However, for the most accurate analysis it is recommended that the standard containing fluorine and/or chlorine be entered as an elemental standard composition. That way, the oxygen can either be calculated by stoichiometry or measured directly along with the halogens. The only missing component then will be hydrogen present in water or hydroxyl which is usually less than 1 % of the total.
Formula Entry