Geological Sciences 231: Mineralogy
Bancroft 2006 Field Trip
Friday, Sept 29 – Monday, Oct 2
Day 1. Friday
7:45am: Meet at Department of Geological Sciences
-Load panel van with gear, load up other vans,
-Directions: take Washtenaw N. to Main St; go N on Main St to M14; take M14 E. to I-75;
go S to Ambassador Bridge towards Windsor Canada; (stop at duty-free shop on USA side);
cross bridge and pass through customs; take Route 3 SE heading for QE401 freeway; stop at
the Ontario Tourist Center (about a half mile to E), get Ontario maps; (stop at Tim Horton’s for
coffee and donuts about 2 miles E on Route 3); continue E on 3 to 401; enter freeway heading to
Toronto; (gas up at rest stop (km 290 E of Kitchener)); (fast food for lunch); look at blocks of
limestone along entrance
Stop 1: Unconformity
-Unconformity visible on N side of Route 7, 1 miles W (before) intersection with Route 62
-Unconformity with sandstone and Trenton limestone over basalt.
Stop 2: Black Marble
-Proceed to Route 62 N
-Black marble on east side of road, 1 mile N of intersection
-Tension gashes and fold vergences show extensional regime.
Overnight accommodations: Silent Lake Provincial Park
-Directions from Stop 2: continue 27 miles N on Route 63 to Bancroft; W on Route 28 past
Paudash ca. 11 miles
-Information: Silent Lake Provincial Park, phone: 613-339-2807; entrance on left (SE) side of
road; showers, flush toilets are available in campground
-Plan: set up camp; make dinner (hamburgers, hot dogs, salad); sleep
Day 2. Saturday
Post-sunrise: get up; breakfast
-Depart from camp; E on Route 28; continue past Bancroft, about 3 miles E of Bancroft on Route
28 about 1 mile E; first road up hill to N. outcrop on west side of road
Stop 3: Princess Sodalite Mine
-Must be there by 9 am
-Veins and masses of blue sodalite behind shop
-Large euhedral dull-grey nepheline phenocrysts cut by narrow sodalite veins
-Nepheline [(Na,K)AlSiO4], sodalite (Na4Al3Si3O12Cl)
Q: how can nepheline become transformed to sodalite?
-Continue E. on Route 28, about 3 miles E of Bancroft off of Route 28; take dirt road on W. side of
river heading N to abandoned quarry 200 yards to N
Stop 4: Throne outcrop
-Tectonic breccia with marble matrix, note field relations, identify coarse minerals that form clasts
-Minerals: calcite, phlogopite, muscovite, hornblende, diopside, aegirine-augite, K-feldspar
-Continue 2.3 miles E. of Bancroft on Route 28; store on N side of road
-Enter mineral shop and ask permission to examine outcrops behind shop
Stop 5: Golding-Keene nepheline pegmatite quarry
-Minerals: nepheline, albite, with minor biotite, zircon, calcite, apatite, sodalite, cancrinite
Q: why is no quartz found in this pegmatite?
-Continue walking E. on dirt road; then take dirt trail over outcrops
-Sapphire and sodalite occurrences
-Total walk: ~half mile, boots recommended, bring hammers, daypacks
Stop 6: Egan Chute gneisses
-Nepheline gneisses with some carbonate layers in chute
-Minerals: diopside, scapolite, hornblende, plagioclase, nepheline, calcite
-Sapphire found here but larger samples all removed
Q: what is sapphire?
-Return to Route 28, cross river, take dirt road on E side of river heading N about 300 yards
Stop 7: York River skarn
-Minerals: garnet, diopside, calcite, feldspar, wollastonite, vesuvianite, forsterite, chondrodite,
spinel, chlorite, zircon
-Possible term project: identification of less common minerals and their assemblage
-Have lunch, return to Route 28, stop at first outcrop 50 feet to E
Stop 8: Marble outcrop
-On Route 28 directly across from dirt road
-Giant rotated mafic clast;
-Identify minerals in marble
-Continue on Route 28E for 1.2 miles
Stop 9: Tourmaline vein in marble
-Red tourmaline in marble outcrop
-Continue E on Route 28, turn N on Fort Stewart Rd., stay on main road, cross over two ridges
about 10 miles N of 28 on left side of road at top of hill, pull into driveway by house
-Ask permission to examine rocks if anyone is home
Stop 10: Pillow lava occurrence (maybe)
-Pillows are small and highly strained, do not show up well if the outcrop is wet
Q: what is significance of pillow lavas? how do they form? what is mineral assemblage in rocks?
-Possible term project: identification of minerals in these rocks
-If time permits, turn left at Bowen Corners to Detlor, L’Amable, then Route 62N to Bancroft
or return S to Route 28, return W through Bancroft on Route 28
-Return to Silent Lake Provincial Park; dinner
Day 3. Sunday
-Directions from Park: E on Route 28 to Paudash, left on Route 121W toward Bicroft/Cardiff, 2
miles NNW, right (ENE) on Monck Rd; drive 2.0 miles, access on W side of white house
-2166 Monck Rd., owned by Mrs. Marg Kerr, N side of road
- ~2 mile hike, take rubber boots, hammers, flashlights
Stop 11: Silver Crater Mine
-Mrs. Kerr expects a fee of $1 per person, leave fee in jar if she is not home
-Park on dirt road on W side of house
-Trail curves past various side road
-Generally well marked with sign or arrow labeled mine (do not walk ahead; easy to get lost if you
don’t know the way, but easy to miss turnoff coming back)
-After passing to the west of a lake going up a hill, take a path NW to mine working and dump
open pit with hornblende, biotited, K-feldspar, some alteration products in coarse marble (or is it
a carbonatite?)
-Giant hornblende, biotite crystals in open pit
-To SW are more workings with large apatite crystals, late purple fluorite in veins
-Some sulfides
-Opaques include uranian pyrochlore, (Ca,U)Nb2O6 (“betafite”), euxenite
-Return to vans, have lunch, drive to orange outcrop 0.3 miles W on Monck Rd
Stop 12: Orange calcite rock
-Head E on Monck Rd.
-Masses of orange carbonate in marble, notice enormous tremolites
-6.6 miles to Route 28, turn left (E)
-Head 1.8 miles E to Bancroft, take Route 62 N out of Bancroft for ca 3.3 miles
Stop 13: Carbonate veins on road N of Bancroft
-Main outcrop on right, veins of carbonate cutting migmatite, at sign “unlawfull to collect”
-Minerals: diopside, scapolite, hornblende, microscopic synchysite and allanite (epidote with REE)
-Continue N for 9 miles on Route 62 past Birds Creek, turn right “Hybla turnoff”
-2.1 miles E turn right on gravel road 0.7 miles to intersection, turn right on gravel road 0.7 mi
-Turn left onto unmarked road, if you miss this turn, stop at mailbox on left labeled MacDonald
return back down road 200 feet, take unmarked diRoute road on right, turn right onto this road,
drive 500’ to small turnaround, park vans, take path overlooking mine take path to left down to
overhang
Stop 14: MacDonald Mine
-Minerals: black garnet (andradite), brown sphene, large, zircon, uranian pyrochlore
(“ellsworthite”), orange calcite, K-feldspar, quartz
-Possible term project: orange calcite and its assemblage
-Return back to main path and head up and over top on right to dumps
-If time permits, turn right, drive loop on Route 62 E to Barry’s Bay, Route 60 to Route 127
cruising for outcrops
-Return S to Bancroft, make pit stop, take Route 28 W to Silent Lake, spaghetti dinner
Day 4. Monday
-Near Miners Bay
Stop 15: Dragon outcrop
-Spectacular back-fold and extreme stretching of fold limbs
-Continue N on Route 12, take Route 60W, Route 11S toward Barrie, Toronto
-Fast food dinner, rest stop E of Kitchener (km 245) continue on 401E
-Pass through customs, take I75N to I94W to Ann Arbor
Next morning before class: meet to clean out vans