Timeline for If a chemical formula for a mineral contains a comma, are there limits on the amounts of each element?
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 14, 2015 at 0:17 | comment | added | Todd Minehardt | Honestly, I don't know - there are enough historical artifacts in re: naming and conventions that it could be the case. There is a reference on Wikipedia that states that in one database (mindat.org), the dominant cation goes first in the parentheses. BUT the International Mineralogical Society is the IUPAC equivalent for minerals since 1959, and if you look at their 2015 master list of mineral names, you'll see the formulae for the 3 minerals here with Mg first and Fe second. | |
| Jul 13, 2015 at 23:37 | comment | added | Ben Norris | If the order of the elements does not tell you anything about the relative composition, then are they listed by increasing atomic number? | |
| Jul 13, 2015 at 16:23 | vote | accept | Elenesski | ||
| Jul 13, 2015 at 16:02 | comment | added | Todd Minehardt | The order of the elements does not tell you anything about the relative amounts of each, as you correctly indicate. The more specific ranges on stoichiometric ratios - indicated above by subscripts and typically seen for minerals in solid-solution series - gives the more specific description. | |
| Jul 13, 2015 at 15:43 | comment | added | R.M. | That answers the specific issue with actinolite, but does not address the more general notational issue. If you have chemical formula that is not more precisely specified, is there any difference between ...$\ce{(Mg,Fe)5}$... and ...$\ce{(Fe,Mg)5}$...? - that is, does the order of elements in the parenthesis tell you anything about the relative amounts of the element in the compound? (The formula given for ferro-actinolite indicates "no", but it would be nice to have it explicit.) | |
| Jul 13, 2015 at 15:06 | history | edited | Todd Minehardt | CC BY-SA 3.0 |
Enhanced answer, included borderline explanation.
|
| Jul 13, 2015 at 14:26 | history | answered | Todd Minehardt | CC BY-SA 3.0 |