Posnjakite
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Description
A blue-green mineral that has been occasionally found as a pigment. Posnjakite occurs naturally in deposits of Malachite. Recipes for the synthetic preparation of posnjakite are given in a late 18th century paint manual (Naumova and Pisareva, 1994). Posnjakite has also been found as a Bronze corrosion product where it is thought to be a precursor to Brochantite formation (Selwyn, et al., 1996).
Synonyms and Related Terms
Posnnakit (Deut.)
| Composition | Cu4SO4(OH)5-H2O |
|---|---|
| Mohs Hardness | 2 - 3 |
Additional Information
° M.Naumova, S.Pisareva,"A Note on the Use of Blue and Green Copper Compounds in Paintings" Studies in Conservation 39:277-283, 1994. ° L.Selwyn, N.Binnie, J.Poitras, M.Laver, D.Downham, "Outdoor Bronze Statues: Analysis of Metal and Surface Samples" Studies in Conservation 41:205-228, 1996.