Field Trip Report - The Dundas Quarry

   Nine in the morning on the third of October, 1999, found about thirty cars lined up at the gates of the Dundas Quarry, 40 km west of Hamilton, Ontario. Quite a few New York plates were noted, as the Buffalo club is now taking part in this collecting weekend. The weather was cold and cloudy, a little on the nippy side but almost perfect for collecting. Click here for a photo showing the size of the quarry.

   After we all signed in, received the standard safety lecture, and drove down into the pit and parked, I began the usual routine of carefully inspecting the big boulders strewn across the floor. Initial inspection was disheartening, as there wasn’t much rock and it didn’t seem very well mineralized, but this is how it usually looks for the first two hours, at least for me. I turned up a nice 25 mm calcite crystal and a very curious micro hopper galena, but the best was yet to come.

   Perhaps fifty meters from where I had parked I came across a fellow sledging a monster boulder, going after fairly nice yellow 2 cm fluorite cubes. Energized by his success I started looking more closely at the boulders in the vicinity and noticed one that was rich in hydrocarbon. This is a resinous black sort of "natural asphalt", and while not actually a mineral is interesting and not often seen in specimens of any richness or size. Down near the base of this rock was a nice pocket about 15 cm across that looked worth investigating, so I took off my backpack and got down to work. Carefully wiggling bits of rock and sand out of the vug revealed numerous bright black sphalerites. These were only up to only five millimeters or so, and not really a big deal, but the luster was outstanding. The pocket was about15 cm deep, and took a while to excavate, eventually yielding a couple of dozen small thumbnail sized specimens, a couple of which were keepers because of their high luster. To see a nice Dundas sphalerite, click here.

   The boulder seemed to be well mineralized and had a nice crack right down the center, so I decided to open it up and see what was inside. I walked back to the car, drove over, and put my sledgehammer to use. The boulder split open with little effort, revealing another nice little vug. And in that vug was a perfect 15 mm galena octahedron, sitting there staring up at me. I simply reached down and picked it up, and attached to it were not only a couple of iridescent sphalerite crystals but a glob of hydrocarbon, with a bit of matrix at the base; a perfect thumbnail sized specimen. This was the second best galena crystal I’ve found in ten years of collecting here, and the only sizeable octahedron, so my day was made. By the standards of a collector in a mid-western US lead/zinc mine it might not even be a keeper, but for a limestone quarry in Ontario, and even for Canada, it’s a pretty decent galena.

   Breaking the boulder down further was much harder, because the two halves were quite solid and uncracked, but I managed to split off a couple more good chunks that afternoon. A few fine sharp 1 cm sphalerites showed up, hiding in small vugs, as well as some nice micro galena; one piece had over 30 crystals to 2 mm, mostly cuboctahedra. A few of the sphalerites had small balls or patches of hydrocarbon on them, and one very unusual 15 mm crystal was only half-formed, because a blob of hydrocarbon had interfered in its development. This is an interesting piece because it indicates that the hydrocarbon was not deposited solely at the end of the sequence; at least some of it formed simultaneously with the sphalerite. Further rock breaking revealed another small vug, which after much excavation and wiggling produced a solid 5 cm chunk of hydrocarbon, the biggest piece I’ve seen. Also from the same boulder came a smooth, lustrous 20 mm "teardrop" of the stuff, quite unusual and actually attractive. Altogether I collected a flat of matrix hydrocarbon and a couple dozen loose coal-like chunks to 2 cm. Some of this material proved to be superb under the scope when I got it home, showing fields of little glossy black botryoids scattered over the brown matrix.

   While searching for a chisel that took flight (It turned up 15 meters away from where I was sledging it!) I noticed another big boulder loaded with medium quality pale yellow fluorite cubes to 2 cm. It produced a half dozen specimens, none were keepers but it was nice finding fluorite that took almost no effort to remove, usually they’re right in the middle of an indestructible boulder. If I had had a drill, or somebody to hold the chisel while I sledged it, some interesting things might have been found in that monster boulder. Click here to see a nice Dundas fluorite.

   The afternoon passed quickly. By quitting time at 3:00 I had split the handle of my big sledge, just about wrecked my poor old crack hammer, and had broken a couple of chisels; but had extracted some nice specimens in exchange. As usual, I went home happy - this quarry produces something new or interesting on every trip. Thanks must be extended to the CCFMS (Central Canadian Federation of Mineralogical Societies) Field Trip Leaders, Bob and Joyce Piech, for organizing the trip.

PLEASE NOTE: This quarry is only open for scheduled field trips.   This is a working quarry, so nobody under 18 is allowed in, and hardhats, steel-toe boots, and safety glasses are mandatory. Contact the CCFMS for more information: http://www.ccfms.ca