Introduction

Moose Point, Guysborough County, is a rather remote location but makes a suitable side trip. It is a shoreline locality with excellent exposures of rock. Large veins of calcite and hematite outcrop on the shore. The specularite variety of hematite is abundant here and makes for interesting specimens for beginner collectors. Tides affect the beach access at this locality.

Geology

These rocks are described by O'Reilly as 'highly faulted Horton Group sediments', roughly 350 million years of age. The rocks are fine grained and listed as shale and siltstone. The faulting due to the location being part of the Cobequid-Chedabucto Fault Zone. A major fault is located just a couple hundred meters to the west at the boundary with rocks of the Mabou Group. Large veins of calcite and hematite can be seen outcropping on the shore.

This locality shares many similarities with nearby Boylston such as the tortured tectonic history of faulting. The mineralogy is also similar though in different proportions, with both having quartz, calcite, iron minerals, with a bit of barite and apatite.

Mineralogy

The mineralogy is fairly simple. Quartz, calcite, hematite, rutile, barite, apatite, and a mica or chlorite are the minerals that have been found.

A comparison to nearby Boylston is also interesting. To contrast, quartz is dominant at Boylston, while hematite and calcite are dominant at Moose Point. At Boylston, iron is instead contained within siderite which is often found decomposed. At both localities the quartz is stained red from the iron and the crystals frequently display Fadens. Also at both localities, small amounts of barite and apatite have been found.

Apatite-(CaF) - Ca₅(PO₄)₃F

A MinDat search turned up an example of apatite found from micromounter's giveaway material at the 2009 Rochester Symposium. The crystal is slightly under 1mm in size. Being the only example I have heard of, I would say that apatite is rare here.

Barite - BaSO₄

Barite has been found as aggregates of small randomly oriented crystals. The crystals are bladed/plates and are light pink in color. They are associated with quartz and hematite. In some examples it has been found growing on top of calcite. Some of the specimens are attractive.

Calcite - CaCO₃

One of the most conspicuous sights at the locality are a couple very large veins of calcite. One is nearly 2 meters across and is banded in color making it quite attractive. Many other veins are open enough to host thousands of scalenohedral crystals. Some can be quite large in size, reaching 10 cm. Unfortunately, most of the calcite is unattractive. It tends to be brown in color due to iron staining. It also tends to be somewhat etched and dull.

Two types of twinned crystals have been found. Crystals twinned according to the {01·2} (structural unit cell) law are the most important as this twin law is rarely distributed worldwide. Still, where it is reported, the twins can be common and Moose Point is no exception. Even within a small section of vein, more then half a dozen examples have been found. Compared to the surrounding scalenohedrons, the twins tend to be larger and are distorted into wedge shapes. This twin law is known from only one other Nova Scotian locality.

Twins following the {10.8} law have also been found. These too tend to be larger than the surrounding crystals and are distorted. They form butterfly twins and wedge shapes. The example below was contacted on the right side, but nicely shows the butterfly shape.

Hematite - Fe³⁺₂O₃

Several large veins of hematite var. specularite outcrop on the shore. The hematite is quite lustrous and flaky. Unfortunately, the crystals are typically intergrown and frost damaged. At least one good specimen has been found, however, in perfect condition. It consists of a cluster of mirror-lustrous lightly striated crystals forming a rosette.

Quartz - SiO₂

In general the quartz is restricted to an accessory mineral. The crystals tend to be small and colorless or milky due to repeated tectonic fracturing. Most are tabular and frequently exhibit Fadens. The often have a red hematite coating, similar to some material from Boylston.

Rutile - TiO₂

Rutile needles have been found to about 1 millmeter in size. They are typically red in color and tend to form bundles of parallel crystals. The are found on a chlorite/mica druze and are sometimes included within the quartz crystals. They are frequently twinned, as is typical for rutile. Some specimens have been found overgrown with a thin layer of hematite.

Conclusions

Moose Point is a nice, isolated beach with several impressive veins of calcite and hematite. A good spot for a novice collector, though care must be taken near the cliffs.

Acknowledgements

Thanks to Terry Collett for allowing me to photograph his hematite specimen. Also thanks to Steve Stuart for use of the apatite photo.

References

O'Reilly, G. (2018) The SPectacular South Manchester Hematite Vein. The Geological Record, Nova Scotia Department of Energy and Mines, 5(3), pp. 5-5.

Richards, R.P. (1999) The Four Twin Laws of Calcite and How to Recognize Them. Rocks and Minerals, 74(5).
http://www.rocksandminerals.org/backissues/rm7405.htm
http://www.findarticles.com/cf_dls/m0GDX/5_74/58243223/p1/article.jhtml

Richards, R.P. (1990) The Origin of Faden Quartz. The Mineralogical Record, 21(3), pp. 191.

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