Bear Lake Diggings, 8.4 km west of Tory Hill, Monmouth Township, 30 km west of Bancroft,Ontario

The Bear Lake Diggings (also known as the Gibson Road Western Occurrence) is one of the top mineral collecting spots in the Bancroft area. This is a fairly large and well-mineralized area, heavily forested and cut by countless trenches up to 3 meters deep, all dug by mineral collectors. The Bear Lake Diggings is a fee site, preserved and regulated by the Bancroft Chamber of Commerce.

Bear Lake's bedrock is primarily gneiss and amphibolite of the Glamorgan Gneiss Complex. The interesting minerals are found in calcite vein-dykes which cut the bedrock in a north-south direction. These veins can be as large as 4 meters wide and 120 meters long, and were formed almost a billion years ago. Millenia of weathering has broken down much of the calcite, releasing the more resistant crystals of apatite-(CaF), titanite, "hornblende", "biotite", and microcline. 

Mineral collector excavating a vein at the Bear Lake Diggings. Most of the crystals are found at the very bottom, screening the soil will yield dozens of nice crystals. Photo courtesy of Alan Goldstein	An enormous apatite-(CaF) crystal,10 by 35 cm, collected in the 1980's. The brown material at the base of the crystal is a plaster base which supports it for display. Photo courtesy of Helen Tyson, of Tyson's Fine Minerals

Bear Lake is world-famous for enormous crystals; thousands of mineral collectors come here every year to dig for crystals. The main mineral of interest is apatite-(CaF), found as green hexagonal prismatic crystals, either loose in the soil or embedded in calcite. They are on average a few cm long, but can be as long as 35 cm and weigh over 30 kilograms! With a bit of luck and hard work, dozens of small crystal sections can be found in an afternoon. Terminations are usually rounded and sort of melted-looking; doubly-terminated crystals aren't too uncommon. Rare pieces of apatite-(CaF) that are transparent and free of fractures can be faceted into beautiful green gemstones.

Apatite-(CaF) 0.56 ct, 7 mm Image courtesy of Brad Wilson

Apatite-(CaF) gem rough, largest piece in the upper right 20 mm long

Lustrous black plates or books of the mica formerly known as "biotite" are fairly common, sometimes as large as 30 cm across. The perfect cleavage makes identification easy. Microcline is found in opaque pale brownish crystals up to 20 cm. "Hornblende") can be found in lustrous black crystals, some as long as 40 cm. Chocolate brown wedge-shaped titanite crystals are relatively rare and highly prized. Most are a few cm across, though crystals to 20 cm have been found which are perhaps the best in North America. 

Other minerals: There are a few other minerals at this locality, but they are relatively rare and usually very small in size. Cavities in large apatite crystals have been found to hold small quartz crystals, minute goethite needles, and reportedly floater calcite crystals. Monazite-(Ce) has been found as rare small excellent crystals on the terminations of apatite crystals. The calcite, which hosts all the other minerals, fluoresces pink under SW UV. The apatite-(CaF) can also be a reddish brown, which is presumably a result of weathering. 

4 cm cluster of "hornblende" crystals, Bear Lake Diggings	Titanite crystal 8 cm across, Bear Lake Diggings

Though known as the Bear Lake Diggings, there are neither bears nor a Bear Lake in the area, though there is plenty of digging to be done. Basic gardening tools like claws and trowels are very handy. A good shovel is the most useful tool to collect with, especially a sturdy small entrenching tool that can be found in army surplus stores. A screen helps to separate the crystals from the earth; building one requires only a piece of steel screen with 1-2 cm openings and a frame made of 1x4 lumber. 

The area is ideal for beginners and youngsters, as the collecting is easy and safe, if common sense is applied. Striking off into the woods by yourself is not the best of ideas, as it is remarkably easy to get turned around and forget where the road is. Bugs can be a problem, and collecting in the bottom of a deep trench with unstable walls is definitely not a good idea. 

Please note that this is a fee site, only accessible if you have previously obtained a permit. Permits are inexpensive, and can be obtained from the Bancroft Chamber of Commerce, the Princess Sodalite Mine Rockshop, and Lakeside Gems.

A fairly typical fluorapatite crystal, Bear Lake Diggings

Mineral list:

More information:

An excellent collecting story - digging out huge fluorapatite crystals

The Minerals of Bear Lake, Ontario, Canada, by Michael Walter

Evidence for the petrogenesis of a calcite vein-dyke complex, Bear Lake Diggings, Monmouth Township, Ontario, Canada - a short technical note on local geology by J.Berry

Calcite vein-dyke complexes in the Bancroft, Ontario region: evidence for a 930 MA carbonatitic intrusive event in the Grenville Province, Ontario - technical information on the age of the deposit by J. Mills

Sabina, A. (1986) Rocks and minerals for the collector; Bancroft - Parry Sound area and Southern Ontario; GSC Misc. Rept. 39, p.90