Me and my buddy Matt went for a trip to Halifax, Nova Scotia this past Saturday (November 26th, 2011) to snoop around the city and try to collect rocks and minerals.
Why snoop around a big city for minerals?
Halifax lies on top of a granitic pluton, a mass of magma located under the surface which has slowly cooled. The batholith intrusion was exposed over a long period of time, over several million years. The granite that you see on most road cuts leading in and out of the city was part of that feature. With igneous rock comes the chance to find interesting crystals. The area is known for its quartz (smoky), feldspar (K-feldspar), tourmaline, pyrite (fool's gold), and gold among other things.
When we arrived in Halifax, we had driven by some road cuts that had yielded several minerals. We parked the car close-by so that we could go take a look before going for a bite to eat. We took some of our gear and headed out to check the outcrops.
The granite contained fine to bigger size grains of quartz, feldspar, and other silicates (pyroxene). We had also spotted some tourmaline and a green mineral that we couldn't identify at the present. We spotten some open veins and Matt peered in some of them, finding this:
This beautiful green crystal was the first thing that we found, and right there made the trip well worth it. Matt will try to get this identified as he hasn't seen anything like this here before. I'll have to update if we get the chance to get this identified.
After lunch we drove to another location in Bayers Lake. This area had yielded in the past large specimens of smoky quartz. Unfortunately, when we arrived at the location, they had built a parking lot on top of it. We stayed around to check a few blocks of granite, probably left over from previous blasting.
There were all sorts of minerals growing on top of each other: feldspar, quartz, tourmaline, mica, some others I didn't recognize.
Pointing at a large smoky quartz
The picture about shows granite displaying odd features. This is probably due to contact between two plutons, causing friction and heat to change the composition. The difference in temperature is shown by the different stages of cooling by layering. From fine crystals when at high temperatures to larger crystals as the rock lowers in temperature.
Not far from here, Matt directed me to drive to another location within Bayers Lake where he had previously found plates of crystals. The outcrop was the remains of previous blasting.
The last location we went to before heading back to Moncton was just outside the city at an industrial park. After walking a bit in the snow, we reached the said so rocks that Matt wanted to show me. These rocks are pyrite bearing rocks: fool's gold. I've seen pyrite samples that came from Halifax that were pretty big.
Matt inspecting the rock for pyrite
Although we didn't find gold or huge specimens, the trip was fun. It was nice to explore Halifax's geology and learning about its formation. I had thought that with snow my traveling would be nil, but come to find out that there is no such thing as taking a break when you're a rock hunter. I've already made plans for more excursions soon, so stay tuned!