Ashcroftine-(Y)
| Ashcroftine-(Y) | |
|---|---|
-257734.jpg) Ashcroftine-(Y) from Quebec | |
| General | |
| Category | Inosilicate |
| Formula | K5Na5(Y,Ca)12Si28O70(OH)2(CO3)8 · 8H2O |
| IMA symbol | Acf-Y |
| Strunz classification | 9.DN.15 |
| Dana classification | 70.03.01.01 |
| Crystal system | Tetragonal |
| Identification | |
| Color | Pink |
| Crystal habit | Acicular to fibrous; intergrowths of fine needle-like crystals; radial-fibrous and matted-fibrous aggregates |
| Cleavage | Perfect on {100}; distinct on {001} |
| Mohs scale hardness | 5 |
| Luster | Vitreous, may be silky |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.61 |
| Optical properties | Uniaxial (+) |
| Refractive index | nω = 1.536–1.537; nε = 1.545–1.549 |
Ashcroftine-(Y) is a rare, hydrous, yttrium-bearing inosilicate mineral containing potassium, sodium, and calcium, together with hydroxide and carbonate anions. Its idealized chemical formula is K5Na5(Y,Ca)12Si28O70(OH)2(CO3)8 · 8H2O. It was named after the British mineral collector Frederick Noel Ashcroft (1878–1949), a benefactor of the British Museum (Natural History).[1][2]
Description
Ashcroftine-(Y) crystallizes in the tetragonal crystal system. It is generally pale pink and transparent to translucent, with a measured specific gravity of 2.61. Its crystals are typically needle-like or fibrous and may occur as fine intergrowths, divergent sprays, or radial-fibrous and matted-fibrous aggregates. Its cleavage is perfect on {100} and distinct on {001}.[1][3]
Occurrence
The type locality is the Narssârssuk pegmatite in southern Greenland, where ashcroftine-(Y) occurs in cavities in alkaline syenite. It has also been found in igneous breccia and pegmatites of the intrusive alkaline gabbro–syenite complex at the Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada, and at Cava dell'Osa, near Rome, Lazio, Italy.[1][2]
Kola ashcroftine phase
A study published on 7 May 2026 described a previously collected, ashcroftine-related mineral phase from the Kirovsky mine in the Khibiny alkaline massif on the Kola Peninsula, Russia. The phase, designated KA, has the idealized formula K6(Na4Ca)(Y8Ca3Mn)[Si28O68(OH)2](CO3)8F2 · 9H2O. It contains calcium, manganese, and fluorine, and its crystal structure includes silicate nanotubules.[4]
See also
References
- 1 2 3 "Ashcroftine-(Y)" (PDF). Handbook of Mineralogy. Mineral Data Publishing. 2001. Retrieved 5 August 2026.
- 1 2 "Ashcroftine-(Y): Mineral information, data and localities". Mindat.org. Hudson Institute of Mineralogy. Retrieved 5 August 2026.
- ↑ "Ashcroftine-(Y) Mineral Data". Webmineral. Retrieved 5 August 2026.
- ↑ Krivovichev, Sergey V.; Yakovenchuk, Victor N.; Goychuk, Olga F.; Kasatkin, Anatoly V.; Pakhomovsky, Yakov A.; Agakhanov, Atali A.; Chernyavsky, Alexey V. (7 May 2026). "Silicate Nanotubules in the Crystal Structure of K6(Na4Ca)(Y8Ca3Mn)[Si28O68(OH)2](CO3)8F2·9H2O, a Mineral Phase from the Khibiny Alkaline Massif (Kola Peninsula, Russia), and the Problem of Ashcroftine-(Y)". Minerals. 16 (5): 492. doi:10.3390/min16050492.
External links
- Ashcroftine-(Y) mineral data at Webmineral
- Ashcroftine-(Y) in the Handbook of Mineralogy