Epidota
Epidota is a mineral with formula Ca₂(Al,Fe)₃(SiO₄)₃(OH), in the Silicato [Sorosilicato (Grupo Epidota)] group. This specimen comes from Knappenwand, Neukirchen am Großvenediger, Pinzgau, Salzburgo, Austria and joined the Terrium collection in 2001.
Description
Floater. Thick, elongated epidote prism of greenish-black colour with stepped natural terminations and very high lustre. Longitudinal striations and good transparency visible in transmitted light (like very dark Duralex green). Shows a few slight contact areas, but the overall condition is very good.
History of this specimen
Originally labelled "Val Antrona, Italy", which was common for Austrian specimens that circulated for decades at fairs in northern Italy. They sold better that way, but habit does not lie. This is a canonical piece.
About Epidota
An absolute classic of European collecting. From the 19th century, the Knappenwand epidotes became emblematic of the birth of modern mineralogy. Museums acquired fine specimens and established the "canon": elongated prisms with stepped terminations, pronounced longitudinal striation and very high vitreous lustre, in shades from pistachio green to greenish black with clean transparency in transmitted light. Complete, sharp floaters, like this one, are today very uncommon due to area protection and depletion of the deposit.
About the locality
Regarded as the finest epidote locality in the world, both aesthetically and crystallographically. Access is now protected and good specimens are increasingly difficult to find on the market. It began in 1865, when Alois Wurnitsch, walking in the Untersulzbachtal valley, came upon an amphibolite lens that appeared open. He dug a little and a cavity full of crystals appeared. He sold some specimens to his friend Andreas Bergmann, a mineral dealer, who sent them to Professor Victor Ritter von Zepharovich for identification; as soon as he saw them he knew what they were. He published a scientific note and the rest is mineralogical history.
Technical data
- Catalogue No.
- 0269
- Composition
- Ca₂(Al,Fe)₃(SiO₄)₃(OH)
- Name
- Epidota
- Group
- Silicato [Sorosilicato (Grupo Epidota)]
- Category
- Cupidium
- Mine
- Knappenwand
- District / Municipality
- Neukirchen am Großvenediger
- Province
- Pinzgau
- Region
- Salzburgo
- Country
- Austria
- Size (cm)
- 3.5 x 3.5 x 2
- Weight
- 40 g
- Acquired
- 2001
- Ex-collection
- Sergio Petetrich
- Etymology
- From the Greek "epidosis", addition or increase, referring to the partial substitution of aluminium by iron in its structure.
- Quality
- Muy buena
- Value trend
- Al alza
Related specimens
- Halita — Austria
- Zoisita (Tanzanita) — Tanzania