In other words, a type specimen is an example that serves to anchor or centralize the defining features of that particular mineral.
A mineral is a scientifically named set that includes some materials and excludes others, based on a detailed published description and on the provision of type specimens, which are usually available to scientists for examination in a major museum research collection, or similar institution.
Hey in 1970 stimulated much discussion on type specimens, leading to formal definitions approved by the IMA in 1987.
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.
[3][4] In plain English, a mineral that already possessed what was believed to be a sufficient definition, that is then subject to reexamination because of the discover of a new specimen.