Killinite: A Re-Examination of Its Status as a Mineral SpeciesAuthor(s): Rab NawazSource: The Irish Naturalists' Journal, Vol. 20, No. 3 (Jul., 1980), pp. 120-122Published by: Irish Naturalists' Journal Ltd.Stable URL: http://www.jstor.org/stable/25538420 .

Accessed: 15/06/2014 19:28

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

Irish Naturalists' Journal Ltd. is collaborating with JSTOR to digitize, preserve and extend access to The IrishNaturalists' Journal.

http://www.jstor.org

This content downloaded from 195.78.108.60 on Sun, 15 Jun 2014 19:28:01 PMAll use subject to JSTOR Terms and Conditions

120 Jr. Nat. J. Vol. 20 No. 5 ivsu

KILLINITE: A RE-EXAMINATION OF ITS STATUS AS A MINERAL SPECIES

Rab Nawaz

Department of Geology, Ulster Museum, Belfast 9

Killinite was described as a new species in 1818 by Taylor from Killiney Bay near

Dublin. Subsequent physical and chemical examination did nothing to prove or disprove its

status as a species. In this study optical and X-ray examination shows that killinite is a 1M

di-octahedral mica akin to hydromuscovite and as such is a variety of muscovite. Chemical

analyses from literature are interpreted and a simple chemical formula derived to show its

relationship with hydromuscovite.

Introduction

Killinite was first discovered'by Taylor (1818) at Killiney Bay near Dublin. Further occurrences were reported from Chesterfield and Branchville, U.S.A., where it was

described as an alteration product of spodumene (Dana 1892, p. 368). On the Irish killinite Dana (1892, p. 369) quotes Thomson (1836) for this pseudomorphous relationship but there is no mention of it in Taylor (1818) or in Gregg and Lettsom (1858). Hey (1962, p. 146) refers to killinite as an aluminosilicate of K, probably identical with muscovite. This paper deals with the status of killinite as a mineral species or variety.

Specimens: Of the five specimens from Killiney Bay, in the Ulster Museum collections four

specimens contain killinite and one specimen contains spodumene but no killinite. Both killinite and spodumene occur as prismatic crystals embedded in the granite matrix. Tests on relative hardness and refractive index tell the two minerals apart. No veins noted by Taylor (1818) are seen in these specimens but the associated minerals are those noted by him with the exception of muscovite which is pearly white and forms anhedral, equant flakes less than 3 mm. Killinite specimens in the British Museum (Natural History) from Killiney

Bay are very similar to those in the Ulster Museum and were not examined further. A small

granite specimen with killinite together with a thin section from Killiney Bay, obtained from the Royal Scottish Museum, was also found to be similar to the Ulster Museum

specimens.

Physical Properties of Killinite: The colour, lustre, fracture characteristics and

hardness of killinite are as noted by Taylor (1818). The crystals of killinite are anhedral, prismatic, up to 5 cm long and 6 mm in cross-section. They are brittle and break up into

elongated splinters. This behaviour is unlike that of micas which produce elastic cleavage flakes. The basal cleavage j 001 [is very good. There are partings parallel to {010} and {110} similar to muscovite (Deer et al. 1963, p 22). There is another parting which is probably parallel to {011>.

Optical Properties: The elongation of the crystals is parallel to the a-axis. The optic orientation of the killinite is similar to that of 1M micas (Deer et. al. 1963, p. 70) in that the

optic plane is parallel to (010) and the X vibration direction is nearly normal to (001). The mineral is biaxial negative and has low to medium 2V. The refractive index values are similar to those of hydromuscovite and illite:

X = 1.545, Y =

1.561, Z = 1.565.

X-ray Study: The X-ray powder diffraction pattern of killinite (Table 1) shows relatively sharp peaks and it shows no changes with ethylene glycol. The orientation was established

This content downloaded from 195.78.108.60 on Sun, 15 Jun 2014 19:28:01 PMAll use subject to JSTOR Terms and Conditions

Ir. Nat. J. Vol. 20 No. 3 1980 121

Table 1. X-ray pattern of killinite from Killiney Bay

d(A) I hkl d(A) I

10.0 70 001 2.45 15 5.0 15 002 2.38 20

4.48 70 020 2.24 10 110

3.65 20 112 2.12 10 3.33 70 022 1.99 15

033 3.07 15 112 1.64 10 broad

2.56 100 200 1.495 50

13T

Cu KX radiation, Camera dia. 114.85 mm.

by means of a rotation pattern about the elongation axis assumed to be the a-axis. The

reflection at about 4.5A is clearly indexable as 020 and 110. This indexing confirms that killinite is a IM mica (Brown 1961, p. 238). Killinite is di-octahedral because the 060 reflection occurs at less than 1.50A and 002 reflection at about 5A is relatively strong.

Table 2. Killinite, cations on the basis of 0 + OH = 24 per unit cell

X Y Z Analysis*

K Ca Fe+3 Li Mg Mn Al Al Si (OH)

a 0.81 0.20 0.32 0.24 ? ? 3.87 1.18 6.82 3.16 b 1.06 0.09 0.21 ? 0.20 ? 2.49 1.95 6.05 8.22

c 0.96 0.10 0.22 ? 0.09 0.13 2.51 2.04 5.96 8.29

Analyses from Gregg and Lettsom (1858), a, by Mallet (1849), b, by Lehunt and c, by Blyth (from Galbraith, 1854).

Chemical Composition of Kilunite: Barker's analysis of killinite as quoted by Taylor (1818) has a low total and hence is unsatisfactory. Gregg and Lettsom (1858) list five further

analyses but two of these have low totals and only the remaining three can be used

profitably. These have been re-calculated on the basis of O + OH = 24 and are shown in Table 2.

These analyses clearly show that killinite is di-octahedral and resembles

hydromuscovites. The X sites contain close to one K atom and it is not certain whether the other K atom is replaced by (H30)+ alone since the H20+ content is not known separately. Analyses b and c yield the simple formula K(HaO)+ Ah Ah SieOi8(OH)5. Analysis a does not show this trend but it is only apparently so because recalculation on anhydrous basis

yields substantially similar results for all three.

Acknowledgements

I would like to thank Peter Embrey, British Museum (Natural History) for allowing me to see killinite specimens, for his help with references and for his comments on an early draft of the manuscript. I am indebted to Harry McPherson, Royal Scottish Museum, for providing information on the killinite specimens and for the loan of a thin section of a killinite bearing rock from Killiney.

This content downloaded from 195.78.108.60 on Sun, 15 Jun 2014 19:28:01 PMAll use subject to JSTOR Terms and Conditions

122 Ir. Nat. J. Vol. 20 No. 3 1980

references

Blyth in Galbraith 1854.

Brown, G., (Editor) (1961) The X-ray identification and crystal structures of clay minerals. London.

Mineralogical Society. Dana, E. S. (1892) The System of Mineralogy of J. D. Dana, 1837-1868, Descriptive mineralogy. 6th Edition.

London.

Deer, W. A. Howie, R. A., and Zussman, J. (1963) Rock-Forming Minerals, 3: Sheet Silicates. London.

Galbraith, J. A. (1854) On the different analyses of killinite. /. Geol. Soc. Dublin 6: 165-167.

Gregg, R. P., and Lettsom, W. G. (1858) Manual of the Mineralogy of Great Britain and Ireland. First published by John Van Voorst, republished by Lapidary Publication in 1977. London.

Hey, M. H. (1962) Chemical index of minerals. 2nd revised Edition, B.M.N.H. London.

Lehunt in Galbraith 1854.

Mallet, J. W. (1849) Notice of a new chemical examination of killinite. /. Geol. Soc. Dublin 4: 142-146.

Taylor, T. (1818) An account of a new mineral substance, discovered at Killiney, in the vicinity of Dublin. Trans. R. Ir. Acad. 13: 3-11.

Thomson, T. (1836) In Dana 1892.

REPORT ON MIGRANT INSECTS IN IRELAND FOR 1979 J. P. Hillis

61 Knocknashee, Goats town, Dublin 14

R. F. Haynes

Little Dorking, Mill Road, Killarney, Co Kerry

This report is made up of records compiled in the usual way (Hillis 1976, 1977, 1978, 1979). It relies almost entirely on the efforts of amateur observers and once again data from

Cape Clear Bird Observatory for Colias croceus (Geoffroy in Fourcroy), Vanessa atalanta

(L.), Cynthia cardui (L.) and Macroglossum stellatarum (L.), form a prominent and

appreciated source of information. The report, following the nomenclature of Kloet & Hincks (1972), presents basic data of occurrence of the main species, marked * in the text, in tabular form (Table 1); it also includes some late data for 1978. Like 1978, 1979 was a

year of mediocre quality for migrant insects.

Notes on the Species

Colias croceus (Geoffroy in Fourcroy) clouded yellow*. Four only, all from Cape Clear.

Vanessa atalanta (L.) red admiral*.

Records started with one on 14 May at the Great Saltee Island, Wexford, but the next was not seen until 11 June at Cape Clear; small numbers were recorded at Cape Clear and other south coastal districts up to late August, when numbers suddenly escalated with 17 to 19 per day on 27-29 and single records from Dublin and Wicklow. Numbers at Cape Clear

continued high during much of September (20 on 9, 30 on 29) and more intermittently, October (40 on 3 and 4, 50 on 16, 20 on 26) with the last ten on 28 October. It was

'unusually common' in Aran, Galway during July and August. Less than 40 records came

from other counties, one 'early in the year' at Grange Con, Wicklow being followed by ones

and twos from late August to early October from several counties of Leinster, Armagh (with 4 on 9 September at Gosford) and Donegal. Two larvae were seen at Pollardstown Fen, Kildare on 31 October.

Cynthia cardui (L.) painted lady.* This species was recorded at Cape Clear from 9 August to 28 October, occurring

almost daily during 14 August-3 September, with peaks of 15 on the 15 and 16 on 29

August; it also enjoyed 'an exceptional year' in Aran, Galway, from 11 July till late August.

This content downloaded from 195.78.108.60 on Sun, 15 Jun 2014 19:28:01 PMAll use subject to JSTOR Terms and Conditions