Hostname: page-component-76fb5796d-qxdb6 Total loading time: 0 Render date: 2024-04-26T13:49:02.201Z Has data issue: false hasContentIssue false
  • English
  • Français

Killalaite, a new mineral from Co. Sligo, Ireland

Published online by Cambridge University Press:  05 July 2018

R. Nawaz
R. Nawaz*
Affiliation:
Dept. of Geology, Ulster Museum, Belfast BT9 5AB, N. Ireland
Get access Rights & Permissions [Opens in a new window]

Summary

Killalaite occurs in a thermally metamorphosed limestone at Killala Bay, near Inishcrone, Co. Sligo. It is a secondary mineral and occurs in cavities and veins with calcite or afwillite in spurrite-wollastonite rocks. It is found in well-formed colourless crystals, up to 2 mm long, with a characteristic penetrative twinning observed under crossed nicols as a cross ‘bow-tie’, cleavage (100) perfect, (010) good, (001) poor. The crystals are monoclinic, biaxial, 2Vα26°, refractive index α 1·635 and γ 1·642, optic axial plane (010), β = [010] (elongation), γ: [001] ≈ 16°, density calculated from RI ∼ 2·88, provisional approximate cell dimensions a 9·3, b 9·9, c 7·7 (±0.1 Å), β ∼105° and Z = 2. Electron microprobe analysis gave CaO 57·o, SiO2 39·8; H2O (by difference) 3·2; MgO, Al2O3, and Fe2O3 together < 0·3 weight %, composition 2Ca3Si2O7.H2O. The stronger lines of the X-ray powder pattern are: 3·03, 2·824, 2·724, 2·275, 2·224, 1·688, 1·673, and 1·413 Å. It probably formed in a CO2-deficient hydrothermal environment in the PT range of 350° to 500 °C and 500 to 3500 bars. The mineral is named after the name of the locality, Killala Bay, and should be pronounced as killalahite. Type material is preserved at the Ulster Museum and at the British Museum (Natural History).

Type
Research Article
Information
Mineralogical Magazine , Volume 39 , Issue 305 , March 1974 , pp. 544 - 548
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1974

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Agrell, (S. O.), 1965. Min. Mag., 34 (Tilley Vol.), 1-15.Google Scholar
Agrell, (S. O.) and GAY, (P.), 196I. Nature,, 189,743.Google Scholar
Emeleus, (C. H.) and Preston, (J.), 1969. Field excursion guide to the Tertiary volcanic rocks of Ireland. Belfast (Dorman & Sons).Google Scholar
Harker, (R. I.), 1959. Amer. Journ. Sci., 257,656-67.CrossRefGoogle Scholar
Harker, (R. I.), 1965. Min. Mag., 34 (Tilley Vol.), 232-6.Google Scholar
Heller, (L.), 1952. [Proc. Third Internat. Symp. Chem. Cement, 237], quoted in Heller and Taylor, Crystallographic Data for the calcium silicates, London (HMSO), 1956.Google Scholar
Mcconnell, (J. D. C.), 1958. Min. Soc. Bull. No. 6.Google Scholar
Mclaugnlin, (R. J.), 1952. In Moody, 1952.Google Scholar
Moody, (K. M.), 1952. Min. Mag., 29, 838.Google Scholar
Nawaz, (R.), 1972. Sci. Proc. Royal Dublin Soc.,Series A, 4, 371-2.Google Scholar
ROY, (D. M.), 1958. Amer. Min., 43, 1009-28.Google Scholar
ROY, (D. M.), Gard, (J. A.), Nicol, (A. W.), and Taylor, (H. F. W.), 1960. Nature,, 188, 1187-8.CrossRefGoogle Scholar
Symes, (R. G.) and Baily, (W. H.), 1879. Geol. Surv. Ireland, Memoir, 53.Google Scholar
Taylor, (H. F. W.), 1955. Acta Cryst., 8, 440.CrossRefGoogle Scholar
Tutrle, (O. F.) and Harker, (R. I.), 1957- Amer. Journ. Sci., 255,226-34.Google Scholar
Van Valkenbura, (A.) and Rynders, (G. F.), 1958. Amer. Min., 43, 1195–1202.Google Scholar