Introduction

McKay Head is located east of Two Islands and Wasson's Bluff, outside of Parrsboro, in Cumberland County. It consists of North Mountain basalt, but the mineralogy is quite distinctive, consisting almost entirely of quartz, calcite, and analcime without significant other zeolites. Nonetheless some superb and interesting specimens have been collected.

History

Being close to both Wasson's Bluff and Two Islands, and not far from Parrsboro, this area was visited by many of the early collectors. Local collector Abraham Gesner describes the location in 1836 (hog tooth spar is calcite),

McKay's Head is a lofty overhanging cliff, affording the most rare and beautiful crystals of siliceous sinter. This mineral occupies geodes and veins in the cliff, and appears under a variety of forms. Stalactical, mamillary, and branching groups of crystals, may be easily procured, imitating flowers, leaves, and a variety of other figures; its lustre is shining, pearly or vitreous and sometimes it is shaded with a light tinge of red. In a large open fissure the sinter is perfectly covered with delicate crystals of hog tooth spar so finely pointed as to wound the fingers when they are incautiously handled.

The spot is also mentioned twice by Albert Bates (1895) as both Moose River Bluff (the river is at the eastern end of the cliffs) and then as McKay's Head. The confusion is likely because the second mention is via another collector named Mr. H. D. Miller of Plainville Connecticut. He didn't realize they were the same location, but based on the descriptions, they clearly are. The text reads,

At Moose River Bluff, Basin of Minas, there occur in the trap rock rosettes and radiating groups of crystals of a pinkish white quartz. The crystals are found in cavities of varying sizes, and may be loosened by a sharp blow of a sledge hammer, but not always with perfect results. A specimen is poorly shown in figure No. 7.

A fine lot of these rosetted crystals is in the collection of Rev. J Seldon Spencer at Tarrytown, N.Y.. Dr. Spencer secured them at the locality several years ago, and they show the careful handling of the experienced collector.

and one paragraph later,

Crystals of milky quartz having a common centre, in ball-like masses, are found loose near McKay's Head, and are curious specimens.

Geology

There are at least a few papers that discuss the rocks at McKay Head (Greenough and Dostal 1992, Schlische and Ackermann 1995). The 1995 paper in particular discusses the distinctive brown veins seen on the bluffs. These are thought to be fissures that formed as the basalt cooled and were later filled with sediments likely during the deposition of the later McCoy Brook Formation rocks seen overlying the basalt at the western end of the bluff.

The veins are quite obvious as they can reach many meters in length and are roughly perpendicular to the layering of the basalt. They also tend to be brown in color and fine grained, contrasting with the gray, sometimes vesicular basalt. These veins contain many pockets of quartz and sinter.

Mineralogy

The mineralogy of McKay Head is quite simple. The most common mineral by far is quartz, with some analcime and calcite, and small amounts of other minerals such as chlorite.

Analcime - NaAlSi₂O₆ · H₂O

Analcime is common as small crystals and druses on quartz and quartz sinter. When clear or white, they add some sparkle to a specimen, but some more interesting examples have been found. The example shown below is green chlorite included analcime crystals. Similar material has been reported from Two Islands, which is just offshore from McKay Head. Henry How writes (1869),

At Two Islands I have found large crystals partly consisting of chlorite lying loose in a cavity, above high water mark, like specimens on the shelf of a cabinet. I have one large crystal of which about half consists of chlorite.

The example below is the brightest color I have seen for analcime from Nova Scotia. This example was one of several from a single pocket collected from a boulder that fell from high on the cliff. The crystals are quite gemmy in places and brilliantly lustrous. The red coloring is nonuniform forming wispy structures within the crystals.

The images below show a crystal with selected edges bevelled. In this case the typical trapezohedron is being modified with the trisoctahedron {233} (Tschernich 1992). This form is quite rare, or at least rarely reported and I'm not aware of any photos other than the one below. The only reports of it that I've been able to find are from the remote Kerguelen Islands (Laspeyres 1877), Table Mountain, Colorado (Cross and Hillebrand 1885), Germany (Brauns 1892), and the Boylstone Quarry, Scotland (Heddle 1899). In the real crystal, a bevel is examined under high magnification shows an uneven line running down the middle of it, as if the material grew in from either side.

A couple nearby crystals show a similar modification, but the 'bevel' is a groove or notch. Analcimes with notches along all edges are very rare, but known from Goble, Oregon and the Keweenaw Peninsula, Michigan (Tschernich 1992), however, the McKay Head examples show the notches only on the select edges approximated by the {233} form. I will try to get an SEM in the future, as it is quite interesting.

Barite - BaSO₄

Terry Collett first discovered tiny white crystals in a boulder that fell from the upper cliff. Better material was found in 2021 showing thin plate-like crystals, sometimes curved. The new material was a visual match for barite; that was confirmed by EDS in late 2021.

Calcite - CaCO₃

Calcite is common, but seems to be limited to tiny crystals. Druzes are sometimes quite fluorescent.

Quartz - SiO₂

Quartz and quartz sinter are very common at McKay Head. The terms sinter, quartz sinter, or siliceous sinter, have been used to describe some of this material since the early days of collecting in the 1800s. In general, these terms are used to describe material formed from hot springs in a watery solution (Akhavan 2005, http://www.quartzpage.de/sinter.html). For the Bay of Fundy material, I am not aware on any analyses differentiating it from regular quartz. But it does have a different appearance than typical quartz, and seems to grade from one to the other.

The quartz commonly forms radial aggregates of milky white crystals that can resemble flowers with an aesthetic effect. In 1997 a significant find was made of this type of quartz, with it being dubbed 'pineapple quartz' (Durstling 1997). The best specimen of collector Hans Durstling is shown below. It is milky white at the pointy end, grading to translucent, grey-white with a faint hint of purple at the base. It is also a floater, with no point of attachment.

Around 2020, a series of pockets were collected that produced a large number of specimens similar to the 1997 find. These consisted of individual doubly terminated crystals, sometimes narrowing at the midpoint of the length of the crystal, clusters of a few crystals, and spherical aggregates of many crystals creating the effect of a sparkly ball. These are quite mesmerizing when seen as a collection of specimens. Most are small, <= 1 cm, but some get to perhaps 4-5 cm in size. Occasionally they will be dotted with tiny analcime crystals. The floaters typically form the most aesthetic pieces, but some good pieces from the pocket walls were also collected. Pieces range from opaque white with a dull luster to translucent with good luster and a faint hint of purple color. On larger clusters, this range of color, luster, and transparency can occur in a single piece grading from one end to the other.

Conclusion

This locality has been a popular destination since collecting began along the Bay of Fundy. It still produces excellent and distinctive quartz specimens and some very interesting examples of analcime and other species.

Acknowledgements

Thanks to Hans Durstling for allowing me to photograph his quartz specimen and to Terry Collett for the barite specimens. Finally thanks to Xiang Yang and SMU for the barite EDS analysis.

References

Akhavan, A.C. (2005) The Quartz Page. http://www.quartzpage.de/index.html (last checked 2020).

Bates, A.C. (1895) Quartz and its Varieties. Arthur Chamberlain publisher, 56 pgs. [Online 2020]

Brauns, R. (1892) Albit, Analcim, Natrolith, Prehnit und Kalkspath, Verwitterungsprodukte eines Diabases von Friedensdorf bei Marburg. Neues Jahrbuch fu¨r Mineralogie, Geologie und Pala¨ontologie: 1892 Bd. 2: 1-24 (4). [Online 2021]

Cross, W., Hillebrand, W.F. (1885) Minerals from the basalt of Table Mountain, Golden, Colorado. Contributions to the Mineralogy of the Rocky Mountains, United States Geological Survey, Bulletin 20: 13-39 (27-29). [Online 2021]

Durstling, H. (1997) The Quartz Balls of Fundy, Nova Scotia, Canada. Mineral News, vol. 13, no. 2.

Gesner, A. (1836) Remarks on the Geology and Mineralogy of Nova Scotia. Gossip and Coade, Halifax, Nova Scotia, 272 pgs.

Greenough, J.D., Dostal, J. (1992) Cooling history and differentiation of a thick North Mountain Basalt flow (Nova Scotia, Canada). Bulleting of Volcanology, 55, 63-73.

Heddle, M.F. (1899) On Analcime with new forms. Transactions of the Edinburgh Geological Society: 7(3): pg 241-243. [Online 2021]

Schlische, R.W., Ackermann, R.V. (1995) Kinematic significance of sediment-filled fissures in the North Mountain Basalt, Fundy rift basin, Nova Scotia, Canada. Journal of Structural Geology, 17(7), 987-996.

Laspeyres, H. (1877) Analcimkrystalle von den Kerguelen-Inseln (Analcime crystals from the Kerguelen Islands). Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde: 1877: 530-530. [Online 2021]

Tschernich, R.W. (1992) Zeolites of the World. Geoscience Press, 563 pgs.

Disclaimer: This page is intended for information purposes only. The locality is not necessarily open to collecting. The locality is not necessarily safe.