Definition of synonym
In mindat.org usage, a simple synonym is a mineral or substance name that means the same as another name. Often these are older names, spelling variants and foreign language versions of names.
Classic examples include:
Disthene is a synonym of kyanite
Iolite is a synonym of cordierite (the name iolite is used more commonly in gemmology).
Chalybite is a synonymm of siderite
Mindat.org continues additionally with the syntax used in several books, such as Hey's Chemical Index of Minerals where a name that can refer to several different minerals, they are each referred to as a 'synonym (in part) of this name. In mindat.org terminology, we refer to this as a multisynonym.
This is used frequently in mindat.org where a previous mineral name has been split into new minerals based on chemical or structural variation, for example with the zeolite group.
A good example is chabazite.
Chabazite is listed as a synonym of chabazite-Ca, chabazite-K, chabazite-Mg, chabazite-Na and chabazite-Sr
This can be confusing at first, because although all chabazite-ca is also chabazite, not all chabazite is chabazite-ca. However, the whole group of names (chabazite-ca, chabazite-k, chabazite-mg, chabazite-na and chabazite-sr) is entirely interchangeable with chabazite, so this syntax is used within mindat.org.
We cannot say chabazite-ca is a variety of chabazite, because chabazite-ca is a unique and valid mineral species in its own right.
The alternative syntax is to use the term 'group' which is used to define related minerals. However, groups are used to define minerals related by physical and/or chemical properties, and often these have wider meanings than the way multisynonym is used in mindat.org. Groups have a more formal creation procedure (usually requiring IMA approval to some extent) so cannot be used in every case.
Classic examples include:
Disthene is a synonym of kyanite
Iolite is a synonym of cordierite (the name iolite is used more commonly in gemmology).
Chalybite is a synonymm of siderite
Mindat.org continues additionally with the syntax used in several books, such as Hey's Chemical Index of Minerals where a name that can refer to several different minerals, they are each referred to as a 'synonym (in part) of this name. In mindat.org terminology, we refer to this as a multisynonym.
This is used frequently in mindat.org where a previous mineral name has been split into new minerals based on chemical or structural variation, for example with the zeolite group.
A good example is chabazite.
Chabazite is listed as a synonym of chabazite-Ca, chabazite-K, chabazite-Mg, chabazite-Na and chabazite-Sr
This can be confusing at first, because although all chabazite-ca is also chabazite, not all chabazite is chabazite-ca. However, the whole group of names (chabazite-ca, chabazite-k, chabazite-mg, chabazite-na and chabazite-sr) is entirely interchangeable with chabazite, so this syntax is used within mindat.org.
We cannot say chabazite-ca is a variety of chabazite, because chabazite-ca is a unique and valid mineral species in its own right.
The alternative syntax is to use the term 'group' which is used to define related minerals. However, groups are used to define minerals related by physical and/or chemical properties, and often these have wider meanings than the way multisynonym is used in mindat.org. Groups have a more formal creation procedure (usually requiring IMA approval to some extent) so cannot be used in every case.