Berzelianite is a rare copper selenide mineral with the formula Cu2Se.[2][3][4] It occurs as thin dendritic crusts or as fine-grained inclusions. It crystallizes in the isometric system,[5][6][7] unlike its dimorph, bellidoite, which crystallizes in the tetragonal system.[8] The crystals are opaque and slightly malleable.
| Berzelianite | |
|---|---|
 Berzelianite included in calcite from the Skrikerum mine in Sweden. | |
| General | |
| Category | Selenide minerals |
| Formula (repeating unit) | Cu2Se |
| IMA symbol | Brz[1] |
| Strunz classification | 2.BA.20 |
| Dana classification | 2.4.10.1 |
| Crystal system | Isometric |
| Identification | |
| Color | Silvery white, tarnishes easily |
| Crystal habit | Dendritic crusts, fine-grained inclusions |
| Cleavage | None |
| Fracture | Uneven |
| Tenacity | Slightly malleable |
| Mohs scale hardness | 2.7 |
| Luster | Metallic |
| Streak | Shining |
| Diaphaneity | Opaque |
| Density | 6.71 (measured) 7.28 (calculated) |
| Ultraviolet fluorescence | None |
| Common impurities | Ag |
| References | [1][2][3] |
Occurrence and name
Berzelianite was first identified at the Skrikerum Mine (also spelled as Skrickerum Mine) in Valdemarsvik, Östergötland, Sweden in 1850.[6]
It was named by James Dwight Dana to honor Jöns Jakob Berzelius, a Swedish chemist who is seen as the father of analytical chemistry. He invented chemical symbol notation and discovered the elements cerium, selenium, silicon, and thorium.[6]
Berzelianite often occurs together with eucairite, clausthalite, tiemannite, umangite, klockmannite, aguilarite, crookesite, athabascaite, stromeyerite, polybasite, pearceite, gold, uraninite, pyrite, marcasite, calcite.