Introduction

Admired for centuries as a place of beauty, the islands represent one of the most beautiful places in the Bay of Fundy - Minas Basin. The dramatic views and effects of the tides inspired native Mi'kmaq legend and continue to inspire visual artists today. For nearly 200 years they have also been the source of many fantastic mineral specimens, including some of the finest gmelinite in the world. Recently it has also become the first Canadian locality for the copper mineral botallackite.

History

As the early settlers travelled mostly by boat around the province, Five Islands attracted much attention with glowing descriptions of their beauty (which are all true). An early map, from 1780 and shown below, names them The Seven Isles, written in old English style. That name really sums up the history of the location - as a recording of erosion in the Minas Basin. The islands get battered by waves and ice, and over time, they have been wearing away.

In more modern times, photography has recorded the size and shape of the islands. As they are photogenic and a fun place to explore, there are many pictures around. I've collected photos from nearly every decade over the last 100 years, from 1915 to present, especially of Pinnacle Rocks. And because they are all of precisely the same location, we are able to observe the rate of erosion over time.

Mineralogically, the richness of the islands has varied over time. In the mid 2000s the islands produced excellent examples of several zeolites. In recent years there have been fewer good finds. This ebb and flow of specimens has occurred before. In McCullochs list, compiled during the late 1700s or early 1800s, the description for Five Islands is "Few minerals, inferior." The primary interest at the islands was the gmelinites, which are described in journal articles of the late 1800s onward. Not only are they very interesting, but the size of the crystals makes them world class. Sadly, since the collape of one of the Pinnacle Rocks in 2004, no large crystals have been found. Smaller ones are still common, but the large ones were found close to a fault and that rock is now gone. Nonetheless new surprises of other species or from other islands, will undoubtedly be unearthed in the future, so we need to keep searching.

Geology

For the geologist, the Five Islands are quite interesting for they are close to the extreme eastern extent of the Bay of Fundy basalts (North Mountain Formation). The basalt overlays the sandstone of the Blomidon Formation and the boundary slopes down to the north. Pinnacle Rocks, the northern half of Pinnacle Island, Long Island, Diamond Island, and the northern half of Moose Island are basalt. The uppermost portion of the Blomidon Formation contains the Triassic-Jurassic boundary. Pollen and spores have been used to study that important point in history (more info).

A county line extends through the islands such that Moose Island is in Colchester County and the remaining islands are in Cumberland County. The community of Five Islands is to the northeast just outside the boundary of the map. Five Islands Provincial Park includes Diamond and Moose Islands, and the mainland east of Moose Island. In addition to land and water, the map below also indicates rock submerged at high tide and the extent of the sand at an extreme low tide.

Mineralogy

A number of fine zeolites have been found in the area including stilbite, natrolite, analcime, gmelinite, chabazite, and heulandite. Calcite is also common. Smaller quantities of magnetite and quartz are found. The sandstone beds of Moose Island contain numerous veins of gypsum var. satin spar. Pe-Piper and Miller report barite and barrerite. One of the things that makes Five Islands interesting is the frequent epimorphing and pseudomorphing of zeolites after other zeolites.

In 2013, I discovered a previously unreported suite of minerals from Moose Island. They form in black rocks found on the beach directly across from Diamond Island at the southwestern end of Moose. The rock must fall from the basalt which at this point is high up on the cliff, so the origin would be difficult to pinpoint. The rock is very solid goethite, but it is magnetic so I suspect a certain percentage is magnetite. Dawson writes a second-hand report of 'sulphuret of copper' and magnetite from nearby Gerrish Mountain (now Economy Mountain) and I believe this is similar material. The copper 'sulphuret' could be chalcocite though other minerals are possible. These hard black rocks are generally solid, but some have tiny pockets and thin mineralized veins. So far I have observed malachite, cuprite, azurite (probably), and botallackite. Botallackite is a rare mineral and this is the first report of it in Canada. In 2015 Sabina listed several new copper sulfide minerals (chalcocite, digenite, roxbyite, spionkopite), botallackite, and atacamite from Five Islands. Another copper sulfide has also been found on Pinnacle Rocks that is anilite (and/or possibly digenite).

Table 1: Minerals reported from Five Islands, Nova Scotia.

I've been gathering evidence that suggests there was an ancient interaction of seawater with these rocks. The first piece of evidence is the presence of barrerite. It has been postulated that barrerite forms by "direct crystallization in the presence of sea water percolating through a volcanic horizon" (Di Renzo 1997). Another is the presence of anhydrite pseudomorphs, with the calcium and sulfate derived from the seawater. The third is the presence of the copper chloride botallackite with the chloride derived from the seawater. Further evidence is found at other localities along the north side of the Bay of Fundy.

Analcime - NaAl(Si₂O₆)·H₂O

Analcime is quite common here and some very attractive specimens has been collected. The crystals may be colorless, white, pink, or brown. Generally they form druses, although these can be quite nice. A few larger crystals to a couple centimeters have also been found.

Analcime epimorphs and pseudomorphs after stilbite were found with the larger natrolite crystals (see later). The stilbite near the pseudos has generally been altered so that it is dull and crumbly. Where the analcime has replaced the stilbite, it forms countless tiny crystals faithfully reproducing the stilbite sheaves, although the relief of the original stilbite was generally poor. The replacements may be solid and complete or may have hollow interiors, occasionally with small natrolite crystals forming in the hollows.

Analcime pseudomorphs after drusy chabazite have also been found from a vein on the north side of Pinnacle Island.

Anilite (and/or Digenite) - Cu₇S₄ (Cu₉S₅)

From Pinnacle Rocks, around 2004, a few rare copper sulfide speciemns were found. The mineral is black and appears to be chalcocite (shown below). One of these crystals was analyzed by EDS and XRD and the results suggest anilite and/or digenite. The EDS gives a copper to sulfur ratio of 1.76, closest to anilite, but the measurement was semiquantitative only, so there will be some error in the measurement. The powder XRD pattern lacks a the strongest peak of the more common chalcocite, so that species can definitely be ruled out. Unfortunately, the powder XRD patterns for anilite and digenite are fairly similar and the results for the Five Islands sample contain features of both. Further complicating matters is the fact that anilite can alter to digenite during the process of grinding the sample to a powder. So, detection of digenite by this method does not mean it was necessarily present in the original sample. Single-crystal XRD overcomes this problem, but I don't want to sacrifice the remaining material for that measurement. There is still the uncertainty regarding the morphology of the crystal. I don't know if anilite or digenite can naturally form that shape or if it might be a pseudomorph after chalcocite, which has been reported elsewhere.

Barite - BaSO₄

Pe-Piper and Miller report barite that "occurs alone or with quartz". That is the first report of the mineral from this area. No further details are given about its appearance or exactly where it was found.

I have a couple specimens from Pinnacle Island that were given to me. The barite forms low mounds with a finely crystallized structure. Visually it does not look like barite, but it has been microprobed. It formed late, on stilbite and heulandite. It is tough, has a radial structure, and is bright white. The mineral is shown in the photo below and in the heulandite photo elsewhere in this article.

Barrerite - (Na,K,Ca_0.5)₂Al₂Si₇O₁₈·7H₂O

Barrerite is a rare mineral first described in 1974 and named in 1975. A second locality in Alaska was discovered only in 1997. It has since been found in many places, but it is rare. Barrerite is visually indistinguishable from stilbite and stellerite and requires analytic techniques for proper identification which is one reason why it can go unnoticed. The underlying symmetry of barrerite distinguishes it from those other minerals. Barrerite was reported by Pe-Piper (2002) from Five Islands, however no description or quantitiative anaylsis is given for the mineral from this locality.

Botallackite - Cu₂(OH)₃Cl

In 2013 I collected some dense black rocks from the beach of Moose Island opposite Diamond Island. These are composed of magnetite and goethite with minor copper secondary minerals forming in thin seams and small pockets. One specimen contained blocky crystals that look like rectangular prisms. They are blue-green in color. These were identified using Raman spectroscopy as botallacite. This is a rare copper secondary mineral, and a polymorph (same chemical formula but different atomic arrangement) of atacamite and clinoatacamite. It is interesting that it contains chloride. Because the rocks were found below the high tide level, I cannot be sure that the crystals did not form after the rocks fell from the beach - deriving the chloride from the seawater. Alternately, the chloride could have been in the rock when it formed. Other minerals found here and at Cape D'Or suggest the latter.

In 2015, Sabina independently reported botallackite and also atacamite from Five Islands. She describes them as 'forming encrustrations and patches on quartz and on chalcedony', which is a different association than what I found.

It is worth noting here that the copper chloride minerals connellite and paratacamite have been found with zeolites at Flinders, Australia (Birch and Pearson 1982). They are very similar to botallackite. Flinders is also a shoreline locality. The authors could not verify the source of the chloride but speculated it was from the seawater.

Calcite - CaCO₃

At Pinnacle Rock, small equant calcite crystals are often found associated with the gmelinite. The crystals are tiny but quite attractive. They are clear and highly lustrous. The dominant rhomb is modified by several forms some of which are striated. The drawing below is simplified, as there are and additional two or three forms that produce faces around the waist. None of the forms shown have been measured yet, but the drawing gives a close feeling for the overall shape of the crystals. Many of the crystals also show signs of twinning.

Cuprite - Cu₂O

I have a single specimen of cuprite from the black rocks of Moose Island. It only forms very tiny massive thin patches, but is easily identified by its bright red color.

Gmelinite-Na - Na₄)[Al₄Si₈O₂₄]·11H₂O and
Chabazite - (Ca,K₂,Na₂)₂[Al₂Si₄O₁₂]₂·12H₂O

The Pinnacle Rocks have produced outstanding examples of gmelinite on chabazite. As described by Tschernich, the pink chabazite has been overgrown by a thin colorless layer of gmelinite. The underlying chabazite is etched with a foamy texture. The gmelinite layer may in places be incomplete so as to leave small openings to the eroded chabazite below. The gmelinite is extremely lustrous and forms triangular growth hillocks. The best examples shown large chabazites to several centimeters in size. These are frequently contact twinned, though penetration twinning is either not obvious or absent.

Most specimens show only gmelinite, but some specimens are associated with little calcites, heulandites, of copper minerals. The calcites can be complex and are sometimes twinned. The heulandites are tan colored and generally etched. The copper minerals are the rarest association. Some specimens recovered near the base of the Pinnacle (near an analcime vein) are topped with tiny scattered analcimes. These are quite attractive and interesting. The analcimes add additional sparkle to the specimens, but the gmelinites are generally quite cavernous and skeletal.

These excellent gmelinites have been reported since the earliest days of collecting around the Bay of Fundy. In 1891, Pirsson performed a complete physical workup on the gmelinite from Five Islands. He writes,

"The zeolites of Nova Scotia have long been noted for the size and perfection of their crystals, and among them gmelinite has held a prominant place." and "In thin section they are seen to be composed of a colorless outer shell or zone, inclosing [sic] a colored inner nucleus. In grinding the sections it was noticed that the outer shell was hard and tough, preserving the crystal boundaries, while the inner portion was spongy, cellular, somewhat friable and readily crumbled away."

In 1924, the Philadelphia Mineralogical Society mentions an expedition to Nova Scotia made by a Mr. Biernbaum, Mr. Frankenfield, and Mr. Broadbelt. They report that,

"a beautiful series of specimens were exhibited, noteworthy among which was a specimen of gmelinite crystals from Pinnacle Island collected by Mr. Frankenfield which measured 9x10cm, the largest crystal which measured 4.5cm across."

If undamaged, this could certainly be a one of the finest specimens ever found. Biernbaum (1927) later published a short report of that trip, but wrote more about the difficulties in getting to and from the islands. He does say however that the gmelinite was "the finest seen by the writer from anywhere."

A modern analsis of the material, including electron microprobe, powder X-ray diffraction, and Raman spectrum can be found in the RRUFF project here.

It is interesting to note that surprisingly similar gmelinites after chabazite have been found in both Kazakhstan and New Jersey. The color and general appearance are strikingly similar, though the crystals are smaller than the best specimens from Five Islands.

Although the specimens are described as gmelinite on chabazite, I had not seen any sign of chabazite in hundreds of specimens. While sorting through some remaining thumbnails for discard, I discovered a single specimen which clearly shows both the gmelinite and the underlying chabazite. It is shown below.

Gypsum - CaSO₄·2H₂O

The satin spar variety of gypsum is abundant on Moose Island. It forms orange to white layers in the sandstone. It formed during intensely arid periods, when the area was a desert (Mertz and Hubert 1989). Gypsum forms in a similar way today in Australia and other places.

Heulandite - (Ca,Na₂)Al₂Si₇O₁₈·6H₂O

Heulandite is not a significant mineral at Five Islands. Some tan crystals have been found associated with the gmelinite from Pinnacle Rocks, however they are generally etched. A few other specimens have been found with better crystals, but they are not common.

Magnetite - Fe³⁺₂Fe²⁺O₄ and
Goethite - Fe³⁺O(OH)

I've found magnetite in thin seams covering the faces of beach worn goethite/magnetite rocks on Moose Island, near the Diamond Island end. Because they were on the beach no complete crystals were found. A few crystal faces did survive, suggesting that well developed crystals could be collected if the material was collected in situ. The source would be high on the cliffs, as the basalt sits on top of the sandstone in this area. A Raman test of one of the rocks indicated goethite, so it appears there is a mixure of the two minerals.

Malachite - Cu₂(CO₃)(OH)₂

Malachite is found in the magnetic black rocks of Moose Island. It is generally massive, though a few small sprays have been found in pockets. It is often associated with a green-blue copper secondary mineral. The second example shown below is much paler green in color, but I've been told by experienced micromounters that this occurs when the malachite needles are very thin and sometimes stepped. That creates a situation where the light has more surfaces to bounce of off before hitting our eye, which is more like the powder/streak color, which is lighter than the bulk mineral color.

Natrolite - Na₂Al₂Si₃O₁₀·2H₂O

Excellent natrolite occurs on the Islands. Both delicate gemmy sprays and large thick white sprays have been found. The larger crystals are several millimeters across and several centimeters in length. They generally form narrowly divergent sprays often connected to form small plates. Many of the larger natrolites were floaters, with small analcime crystals sometimes attached to the base of the sprays and the whole found on top of stilbite.

Quartz - SiO₂

In the 2000's there was a noteworthy pocket of amethyst found on the beach of Moose Island. As the story was told to me, a visitor found half of the pocket. Another visitor offered to buy the pocket was was turned down. He then thought the other half of the pocket might still be on the beach. He went searching for it and found the other half! There was photographic evidence showing a superb, large and deeply colored specimen.

After Pinnacle Rock collapsed in 2004, opaque white pseudomorphs were found. The original mineral is likely anhyrite as bladed crystals. Using microprobe these have been shown to be quartz now. They are crumbly and rarely complete. They can be quite dense, forming masses to a couple centimeters thick, mixed with a soft, dark, altered basalt. They were found associated with the gmelinite, and in some cases are intergrown with the gmelinite. I have seen crystals growing in the etched out underside of gmelinites, and also small gmelinites growing on the anhydrite.

Although anhydrite from the basalts seems unusual at first, it is well known from the basalts in New Jersey. There it is found both as large masses and also as casts where other minerals have overgrown anhydrite crystals and later the anhydrite dissolved away.

Stilbite - NaCa₄Al₈Si₂₈O₇₂·30H₂O

The most interesting stilbite from the Islands are bright pumpkin orange drusy plates and mounds. While generally showing little relief, the color is the some of the best for stilbite from the province. In some cases calcites are found on top of the stilbite. These were in turn overgrown by a very thin fine druse of second generation stilbite. The calcites are generally etched, perhaps due to the secondary stilbite fluids.

Conclusions

Five Islands in one of the most beautiful spots in Nova Scotia. The islands have also produced many fine examples of zeolites. Specimens of natrolite and gmelinite rank highly for their species. There are many examples of multiple generations of mineral formation and pseudomorphing that add interest to the specimens. Some copper mineralization adds even more interest for the micromineral collector.

Acknowledgements

Thanks to Don Doell and RRUFF for the botallackite identification. Also thanks to Terry Collett for allowing me to photograph specimens from is collection, and to Terry and Doug Wilson for the specimens with barite. Most of all, thanks to Roger Hunter for saving us from the rocks when the storm came in!

References

Biernbaum, Morrell G. (1927) "Famous Localities of the World; The Zeolite Localities of Nova Scotia", Rocks and Minerals, vol. 2, no. 4, pp 126-127.

Birch, W.D. and Pearson, J.E. (1982) Copper chloride minerals in basalt from Flinders, Victoria. Australian Mineralogist, 39, 211-213.

Dawson, Sir J.W. (1855) Acadian Geology, Oliver and Boyd, 388 p. [Online 2015]

Des Barres, J.F.W. (1780) The isthmus of Nova Scotia. Atlantic Neptune, London. [Online 2020]

Di Renzo F. and Gabelica Z. (1997) "Barrerite and other zeolites from Kuiu and Kupreanof Islands, Alaska", The Canadian Mineralogist, 35, 691-698.

Gordon, S.G. (1924) "Proceedings of Societies, Philadelphia Mineralogical Society, Academy of Natural Science, Sept 11, 1924", American Mineralogist, vol. 9, no. 11, pg 231-232. [Online 2015]

Howe, A.B. (1876) "Gmelinite from Nova Scotia", The American Journal of Science, 719-720. [Online 2015]

Jackson, C.T. and Alger, F. (1834) "Remarks on the Mineralogy and Geology of Nova Scotia". [Online 2015]

Mertz, K.A. Jr. and Hubert J.F. (1989) "Cycles of sand-flat sandstone and playa-lacustrine mudstone in the Triassic-Jurassic Blomidon redbeds, Fundy rift basin, Nova Scoti: implications for techtonic and climatic controls", Canadian Journal of Earth Sciences, 27, 442-451. [Online 2015]

McCulloch, Rev. T. (1892) "List of Localities for Trap Minerals in Nova Scotia", Proceedings and Transactions of the Nova Scotian Institute of Science, 8(2), pp. 160-166. [Online 2015]

Pe-Piper, G. and Miller, L. (2002) "Zeolite minerals from the North Shore of the Minas Basin, Nova Scotia", Atlantic Geology, 38, pp. 11-28. [Online 2015]

Pirsson, L.V. (1891) "Gmelinite from Nova Scotia", American Journal of Science, Series III, vol. 42, art. 8, pp. 57-63. [Online 2015].

Schaller, W.T. (1932) "The Crystal Cavities of the New Jersey Zeolite Region", U.S. Geological Survey, Bulletin 832, 1932. [Online 2015]

Tschernich, R.W. (1992) "Zeolites of the World", Geoscience Press, Phoenix. [Online 2015]

Walker, T.L., and Parsons, A.L. (1922) "The Zeolites of Nova Scotia", Contributions to Canadian Mineralogy, University of Toronto Press, pp. 13-73.

Wallace, P. (1998) Five Islands Provincial Park. in Discovering Rocks, Minerals, and Fossils in Atlantic Canada: A Geology Field Guide to Selected Sites in NF, NS, PEI, and NB. Atlantic Geoscience Society Special Publications, 67-70.

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