Cassidyite mineral
Cassidyite (IMA 1966-024) is an IMA-accepted hydrated calcium-nickel phosphate mineral of the fairfieldite-collinsite group, the nickel analogue of collinsite, with IMA September 2026 Master List formula Ca2Ni(PO4)2(H2O)2 and solid-solution composition Ca2(Ni,Mg)(PO4)2·2H2O (with Ni:Mg ranging from 3:2 to 3:7). Described by White, Henderson, and Mason (1967) from weathered meteoritic iron shale at the Wolf Creek meteorite crater (19°18'S, 127°46'E), Western Australia, Australia (type specimen USNM 119553), where it forms pale green to bright green crusts and small spherules in cracks and cavities alongside lipscombite, pecoraite, and reevesite via weathering of schreibersite (Fe,Ni)3P. Electron microprobe analysis (pp. 1194–1195) gives mean CaO = 32.3 wt% and P2O5 = 39.2 wt%, with NiO 6.4–16.2 wt% and MgO 5.7–2.2 wt% (Fe not detected; CoO-equivalent ~0.4 wt%), spanning nickelian collinsite to magnesian cassidyite. Triclinic (space group P-1), with nominal unit-cell dimensions a = 5.71 Å, b = 6.73 Å, c = 5.41 Å, alpha = 96°49', beta = 107°22', gamma = 104°35', V = 190 Å3, Z = 1, density 3.1–3.2 g/cm3 inferred from calculated endmembers (2.96 g/cm3 for the Mg endmember and 3.26 g/cm3 for the Ni endmember; direct measurement precluded by admixtures and fine grain size), and refractive indices alpha = 1.64–1.65 and gamma = 1.67–1.68.
Explore across X-Mech: MediaIngredientMech · CultureMech · CommunityMech · HabitatMech · TraitMech · CMMMech Network Graph
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| IMA |
IMA:1966-024
|
Cassidyite |
Sources & References
-
ima_2026_09: IMA-CNMNC (Pasero M., 2026), The New IMA List of Minerals – A Work in Progress (Updated: September 2026), PDF p. 38, Cassidyite row: status A, IMA 1966-024, formula Ca2Ni(PO4)2(H2O)2, reference White J.S., Henderson E.P., Mason B. (1967) American Mineralogist 52, 1190-1197.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24) -
white_1967_cassidyite: White JS Jr, Henderson EP, and Mason B (1967), Secondary minerals produced by weathering of the Wolf Creek meteorite, American Mineralogist 52:1190-1197.
https://www.rruff.net/doclib/am/vol52/AM52_1190.pdf (accessed 2026-10-24)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-24T07:30:00Z |
antigravity | CREATE | Created mineral record for Cassidyite (IMA:1966-024) from the IMA September 2026 Master List and the primary type-description paper by White, Henderson, and Mason (1967) in American Mineralogist 52:1190-1197. |
2026-10-24T10:45:00Z |
antigravity | EDIT | Resolved CMM120-F7 (issue #838) by replacing the unsupported R. C. Walls wet-chemical assay, Ni0.55Mg0.45 formula, measured SG claim, and cell uncertainties with the pp. 1194–1195 electron microprobe prose, nominal triclinic cell (alpha = 96°49'), and inferred 3.1–3.2 g/cm3 density from calculated endmembers (2.96 and 3.26 g/cm3), and simplifying sources[1].title to a concise bibliographic citation. |
Record source: data/records/cassidyite.yaml