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Mineralogical ClassificationWhat is the definition of a "type ocation"?

17th Aug 2016 15:31 UTCSue

I have never seen it defined. Is it the location of the most TYPICAL specimen of the mineral or the BEST element of the mineral or where the mineral was DISCOVERED? Thank you.

17th Aug 2016 16:20 UTCHarold Moritz 🌟 Expert

http://www.mindat.org/glossary/type_locality

"The type locality of a mineral is the locality where the original material came from for the formal definition of the mineral species."

Ideally this is also a very specific place that mineralogists can return to for additional material for further study, etc., and is a place where the mineral is found in situ, so that it's geological environment of formation is known. However, in many cases, the type locality is poorly described and/or lost, such as for danburite, or in the case of chrysoberyl the type locality is the very unspecific "Brazil" because they were found there ex situ in stream gravel. Arguably, the true type locality for chrysoberyl should be at a place in Haddam, Connecticut where it was first found in situ in 1810. Sometimes they are also just wrong, like tungstite, which is assigned to Lane's Mine in Monroe, but is actually from Lane's Mine in Trumbull, Connecticut.

I'm not sure when the idea of assigning these formally came about, or who officially assigns them, but it was not an idea that started with the science of mineralogy, it came along after many minerals had long been described. Today there is an emphasis on carefully documenting the type locality, but as late as the mid-19th century such things were not a priority, hence some of the problems noted above.

Also note that the definition hinges on the first formal definition of the mineral. Many minerals were found in other places first but were not recognized then as new species. For example, wodginite, the co-type localities being the Wodgina tantalite mine in Australia, Tanco Mine in Canada, from where it was first described in 1963. But many crystals were collected in the 1940s and 1950s from the Strickland Quarry in Connecticut, but were misidentified as other minerals and thus it is not the type locality.

17th Aug 2016 17:18 UTCDavid Von Bargen Manager

The type specimen is the specimen which was used to determine the properties of the species (usually the crystallography and chemical composition of the species). These specimens are usually preserved in a museum, so they can be studied in the future and used to compare to new material. This may be one or more specimens and the type locality is simply where these specimens originated.

17th Aug 2016 18:12 UTCPaul De Bondt Manager

The TL is not always where the first specimens where found.

See for azurite. The LT is Chessy in France. But the mineral was found almost 2000 years before in Laurium, and perhaps earlier on even more obscure localities.

Cheers.

Paul.

17th Aug 2016 19:04 UTCAlfredo Petrov Manager

The "type locality" is the locality from which the "type specimen" came, not the place where the mineral was first found. The type specimen is the one(s) used for first describing the mineral (ie. chemistry, structure, physical properties).

In the case of minerals described after 1959 (when the IMA was founded), the type specimen(s) (and therefore usually also the "type locality") is pretty well defined. But for pre-1959 minerals there is very often no type specimen, the mineral having been described incompletely, in stages, from various places. So in such cases the type locality can be rather nebulous. Is the type locality then the place it was first found and recognized as something new? ...or the place from which it was first (inadequately) described? ...or the place where the name was first used? ...or the place from where a more complete description was first made? In many such cases the "type locality" for the mineral is more a matter of opinion than science, and various references will disagree with each other. And to put the topic into perspective, we should note that it is mainly of interest to collectors, and isn't of much importance to professional mineralogists, for whom the important question is "Is there a type specimen we can access for further research?" (If not, then the subject of type locality is moot, at least for the mineralogists.)

17th Aug 2016 19:43 UTCDavid Von Bargen Manager

If the type specimen is lost and the mineralogist is really gung ho, the type locality may not be moot. One could go to the type locality and collect more of the material and if it matches, the new specimen could be declared as a type specimen (neotype).

18th Aug 2016 02:08 UTCDoug Daniels

One could return to the type locality and collect new specimens only if it still exists - that is, it hasn't been mined out, mined away (such as with open pits), or the area reclaimed (environmental clean-up).

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