Type specimen (mineralogy)
In mineralogy, the type specimen, also known as type material, is a reference sample by which a mineral is defined.[1]
Types
The following definitions for kinds of type specimens were approved in 1987 by the Commission on New Minerals and Mineral Names and the Commission on Museums of the International Mineralogical Association (IMA).[1]
- Holotype
A holotype is a single specimen from which the original description of the mineral can be determined in whole.[1]
- Cotype
Cotypes are multiple specimens from which quantitative, but not necessary, data are obtained for the original mineral description.[2]
- Neotype
A neotype is a new specimen for the redefinition or reexamination of a mineral when the holotype or cotypes cannot be located or, upon examination, are inadequate for study.[1]
Purpose
Type specimens are valuable when a mineral species is reevaluated because the original description of a mineral may be incomplete or contain errors.[3][4]
History
Whereas the system of type specimens has long-existed in the biological sciences, this is not the case in mineralogy. The recentness of the practice means that sometimes no type material exists, even for minerals discovered as recently as the twentieth century.[1] The publication of "Type specimens in mineralogy" by P.G. Embrey and M.H. Hey in 1970 stimulated much discussion on type specimens, leading to formal definitions approved by the IMA in 1987.[2]
Nowadays, deposition of the type material in a professionally curated museum is required by the Commission on New Minerals, Nomenclature and Classification of the IMA when approving a new mineral species.[3]
References
- Bibliography
- Dunn, Pete J.; Mandarino, Joseph A. (November–December 1987). "Formal definitions of type mineral specimens" (PDF). American Mineralogist. 72 (11 & 12): 1269–1270.
- Nickel, Ernest H.; Grice, Joel D. (1998). "The IMA Commission on New Minerals and Mineral Names: Procedure and Guidelines on Mineral Nomenclature, 1998" (PDF). The Canadian Mineralogist. 36.