Museum mineralogist Paula Piilonen and research assistant Glenn Poirier spent a week in August as part of a geological mapping project on Baffin Island in Nunavut. Read Paula’s account of how it went.
Our plan for the first day in the field was to visit a gem spinel locality 25 minutes east of camp, first described about 10 years ago by a geologist with the Department of Indian Affairs and Northern Development. I was eager and excited to be off—this was to be my first ride in a helicopter!
After assuring the pilot, Jim, that I wasn’t going to get airsick, we took off and headed to what we will call ‘Marble Valley’. Flying in a helicopter is an experience like no other—it’s totally incredible, a feeling of floating rather than true flying. Flying over the edge of a fjord gave me almost a sense of vertigo, especially when the tundra dropped away beneath my feet and I was suddenly staring down at a river 1 000 feet below. But I must admit, it’s a great way to commute to work every day!
The helicopter pilot dropped us off at the top of one hill and we spent the day looking at outcrops up and down (vertically and horizontally) on the cliff sides, scree slopes and boulder fields, staring at white marble. We did find numerous pods of the spinel, which is a group of minerals that can be refined as gems. These pods were light blue to dark purple in colour, with some large euhedral octahedral crystals (up to half a centimetre) and some with gem potential, if you wanted to cut something that small.
The one thing we discovered is that distances are deceiving when you’re on the tundra and in a fjord. A distance we thought we could cover in one day (from the air) turned out to be very ambitious on the ground! And in some places quite dangerous—’boulder ballet’ is not advised when you are carrying 23 kg of rocks, survival equipment, satellite phones and water on your back!
We spent two full days in Marble Valley, searching for spinels and a granitic pegmatite, of which we had found blocks on the lower levels of the valley slopes. The blocks were at the bottom of the cliffs, so on the second day we had the helicopter pilot drop us off at the top of the cliff as we did our best impressions of mountaineers and scaled down the cliff faces to collect the elusive pegmatite.
We found the granitic pegmatite (400 metres long, 40 metres wide at least), but it was ‘barren’ with only a bit of smokey quartz. It did; however, have some nice graphic granite textures.
The real find for us was at the contacts with the pegmatite where there has been some metasomatic activity and the formation of calc-silicate skarn-like pods/zones.
The first locality yielded some beautiful euhedral graphite crystals in a diopside matrix – definitely collection worthy. At the second location, we found awesome, black augite crystals with gem potential, as well as huge biotite books (so-called because they resemble a book with many pages of sheets). These things were large – 12 inches across and some of them were 8 to 10 inches thick! Many of these augite and biotite crystals were collected and brought back to be incorporated into the national mineral collection.
After each day in the field, the entire field crew—staff from the Canada-Nunavut Geoscience Office, geologists from the Geological Survey of Canada, undergraduate and graduate students—would gather in the communications tent and have a ‘geowrap’ session before the call for supper.
Part geological discussion about the day’s work, part show-and-tell, this offered a chance for everyone to debrief and plan for the next day. Our collecting in Marble Valley certainly added a few “pretty” samples to the collection of Archean gneisses, metavolcanics and metasediments.
During our last day in the field, we had the opportunity to fly to Napoleon Bay along the coast to check out a locality originally discovered and described by Dr. Don Hogarth, Professor Emeritus at the University of Ottawa.
Intruded into the Archean gneiss are fine grained, dark-brown to black dikes of a rare alkaline rock called lamproite. These lamproites, dating to about 1.24 billion years old, contain a suite of rare minerals found only in alkaline rocks—a virtual treasure trove for us with a possibility of many new mineral species.
Now, having returned to the lab at the museum’s research and collections facility, we are slowly unpacking and examining the 90 kg of rock that we brought home with us as ‘extra luggage’.
Each sample brings back memories of time spent as far away from our technology-filled labs as one could possibly get—memories of working in Nature’s own lab in a part of our country where geology is exposed everywhere you look.
We are now carefully analysing each sample under a binocular microscope. If we don’t know what the minerals are, they will be X-rayed to determine the species name and then analysed by electron microprobe to determine their chemistry.
We’ll keep readers up to date on our progress!