Petrology, GEO-320 – Kurt Hollocher

I have retired, and so this course is no longer taught by me. I have abbreviated the content of this page to remove course-specific rubbish and content getting increasingly out of date. If you find any of the things here useful, that’s good.

Special documents	Syllabus
	Using petrographic microscopes: adjustments and features
	Thin section collections
Igneous rock labs	White Mountain magma series	WMMS photo gallery
	New Hampshire magma series	NHMS photo gallery
	Skaergaard and Stillwater intrusions	Skaergaard photo gallery, Stillwater photo gallery
	Iceland lavas	Iceland photo gallery
Metamorphic rock labs	New England schists	New England geology 1, 2; metamorphism 1, 2 Photo gallery
	New England mafic rocks	New England geology 1, 2; metamorphism 1, 2 Photo gallery
	Norwegian eclogites	Fennoscandia geologic map, very simplified map Photo gallery
	Fault rocks	Fault rocks photo gallery
Forms and graph paper	Rock report form Ternary graph paper, and a green one
Documents and spreadsheet utilities	Writing igneous rock hand sample descriptions Writing metamorphic rock hand sample descriptions Why petrology is so much fun
	How to calculate norms from rock chemical analyses NORM4 norm spreadsheet for single samples NORM4 macro-enabled version for multiple samples (file type not allowed here, ask me for a copy)
	Estimating Fe³⁺ in amphiboles Estimating Fe³⁺ in biotite Making thin sections Staining feldspars in thin section
	Fill in missing values on REE diagrams! Make ternary (triangle) diagrams in spreadsheets! Whole rock geochemical discriminant diagrams!
Image libraries	Igneous minerals in thin section Igneous textures in thin section Metamorphic minerals in thin section Metamorphic reactions in thin section Metamorphic microstructures in thin section Moon rocks Hand sketches in petrology

SVG vector graphics files for figures I use in this course (native Inkscape).

Assorted field trip images

Ferrosyentie dike cutting leuconorite, summit of Mt. Jo.
Nice graded quartzite bed. Top is to the upper left.
Looking at a thin ferrogabbro dike crosscutting anorthosite.
Looking for graphite in marble, Warrensburg, NY.
Big garnet outcrop, Warrensburg, NY.
Searching for mega-samples, as usual.
Large sillimanite pseudomorph after andalusite, ~35 cm long.
Magnetite ore body and mine west of Ticonderoga, NY.
Looking at Clough Quartzite, Cragg Mountain trail, Northfield, MA.
Early risers in Petrology, 2004.
Large tourmaline crystals in a quartz vein. Longest crystal is ~4 cm.
Blue calcite!
Woodchuck on Jurassic red bed sediments, Turners Falls, MA.
Boulder cave exit.
The two notches in the outcrop are weathered out alkali basalt (camptonite?) dikes cutting leuconorite, near the summit of Mt. Jo.
More isoclinally folded quartzite beds.
The true breakfast, lunch, and dinner of champions.
Isoclinally folded quartzite beds.
Even more lunch.
Petrology, 2000. Sarah, Nick, Mike, Bill, Sarah, Jeremy on the summit.
More lunch on Black Precipice.
Large plagioclase megacryst in anorthosite, Mt. Jo.
Contact between a granitic gneiss (light colored center and right) and a garnet amphibolite (lower left).
Natural Bridge, in Natural Bridge State Park, North Adams, MA.
Eroded lamprophyre dike, near the summit of Mt. Jo.
Hornblende-diopside-plagioclase-calcite vein in an amphibolite ‘xenolith’ in the deformed marble, banks of the Hudson River.
More folded quartzite beds. Wind is gusting to 50 mph.
Late fault offsetting quartzite layer.
Folded quartzite beds.
Outcrop of Clough Quartzite on Crag Mountain, Erving, Massachusetts. View to south-southeast toward the Northfield Mountain pumped storage reservoir in the Pelham Dome.
Rainwater pool off the main trail, looking southeast toward Bald Rock.
Tonalitic gneisses and amphibolites at the Shelburne Falls, Shelburne Falls, Massachusetts.
Chicken track pattern of andalumps on a foliation surface.
Late quartz vein with 25 cm wide tourmalinized zone around the vein.
Looking back toward the summit from Bald Rock, on the way to the graphite mine and the boulder cave.
David pops out of the boulder cave.
Patrick pops out of the boulder cave.
Coticule layer near the Billings Fold.
Walloomsac metamorphosed calcareous sandstone, Rt. 8, North Adams, MA.
Lunch on Black Precipice, looking south at the landscape.
Sarah, done with her sandwich. Not sure if it was the finest.
Pre-hike lunch making. Nothing better than peanut butter and jelly!
Coarse-grained marble on the shores of the Hudson River.
Looking down on Heart Lake, adjacent to the Adirondack Loj campground.
Brian pops out of the boulder cave.
View to the east from the summit. Boston was not visible today.
Off the trail looking at complex isoclinal folds and graded quartzite beds.
Looking at leuconorite, cut by numerous ferrosyenite dikes that form an extremely block-rich intrusion breccia.
Halfway house site, with andalump schist and pegmatite.
Nice red garnets. The schists contain red garnets up to 2 cm across.
Checking out an especially large muscovite crystal in a pegmatite dike.
Looking closely at the corona textures and the green plagioclase flow foliation in a corona gabbro, near Schroon Lake.
Large tourmaline crystals in a quartz vein. Largest crystal is ~5 cm long.
Cambrian Cheshire quartzite on Pine Cobble, Williamstown, Massachusetts.
Group photo from Pine Cobble, Williamstown, Massachusetts. Stop 4 at 9:00 AM.
Salamander escapes from tent caterpillar.
Looking at metamorphosed quartz pebble conglomerate in the Cheshire Quartzite, Pine Cobble Trail, Williamstown, MA.
Alkali basalt dike cutting leuconorite, on the long trail down from the summit of Mt. Jo.
Large twinned plagioclase, summit of Mt. Jo, in an anorthosite block within the leuconorite.
Eroded lamprophyre dike, near the summit of Mt. Jo.
Coming down from the summit. It’s actually not as steep as it looks.
Group photo on Crag Mountain, Erving, Massachusetts, view to northeast.
Largest plagioclase megacryst in anorthosite, Mt. Jo.
Mylonite zone cutting gabbroic anorthosite, Keene Valley.
Metamorphosed Cambro-Ordovician volcaniclastic sediments on the east side of the Berkshires. Abundant quartz veins and glacial striations.
Summit of Monadnock.
Salamander rushes off at top speed.
Anna pops out of the boulder cave.
Normal-size samples are sufficient for normal people.
Feeling for fault movement indicators on a slickensided surface, Waloomsac Formation, Rt. 8, North Adams, Massachusetts.
Small fault with calcite infilling, cutting calc-silicate block in marble, Paradox.
Trying to get out to the outcrop in the middle of the river, Jay.
Deformed xenolith breccia in gabbroic rocks, as part of the older plutonic complex in the roots of the Taconian island arc. Shelburne Falls.
Bill, hanging up.
Sarah and Sarah walking up to Bald Rock.
Summit of Mt. Jo.
Eroded lamprophyre dike, near the summit of Mt. Jo.
Infold of marble and calc-silicate layers into a partially separated amphibolite boudin neck, banks of the Hudson River.
Silurian Clough quartzite, Crag Mountain, just west of the Connecticut River valley.
On the hike down we found another part of the Billings Fold, ~200 m along the axial surface.
Metamorphosed limestone of the West Stockbridge Formation, North Adams, Massachusetts.
Summit of Monta Rosa, with tourmaline veins, garnets, andalumps, and sillimanite fibers.
A new friend.
Coarse-grained, intensely folded graphite- and diopside-bearing marble on the shores of the Hudson River, Warrensburg, NY.
Labradorite showing labradorescence. It is caused by a diffraction effect from closely-spaced exsolution lamellae.
Large xenolith choking the interior of a thin tourmaline granite sill.
Snoozing on the flysch and chips outcrop, eastern Berkshires, Massachusetts.
The whole hiking crew.
Off the main trail, looking toward the summit.
Metamorphosed tonalitic intrusives of the Taconian arc complex, Shelburne Falls, MA.
Highly deformed marble on the shores of the Hudson River.
Bill reading the paper.
Nick and Bill hanging out.
Graded quartzite bed, stratigraphic top to the upper right.
Portrait of an unhappy snake.
Samples of magnetite-garnet sand, Schroon River.
“Billings Fold” near the Monadnock summit.
Well, it beats PB and J again.
Black Precipice for lunch.
If you are going to take a snooze, it might as well be in a nice spot!
Looking back from the location above to the Billings Fold itself.
Lunch on Black Precipice. Garnet- and tourmaline-bearing granite dikes and sills visible in the schist.
And snacks, too!
Crossing Roaring Brook on the way to some outcrops, Giant Mountain, Adirondacks.
Another group photo at Pine Cobble, Williamstown, Massachusetts. Stop 4 at 9:00 AM. Photo donated by Ralf Schauer.
Large quartz mass in the neck between two large amphibolite boudins in marble, Paradox.
Boulder cave exit, again.
Part of the class.
Looking at a quartz-pebble conglomerate in the Cheshire Quartzite, about half way up the trail to Pine Cobble, Williamstown.
View from the summit to the south, toward Bald Rock (left) and the halfway house site (right).
Metamorphosed tonalitic intrusives of the Taconian arc complex, Shelburne Falls, MA.
Deformed marble with numerous ‘xenolith’ blocks and folded layers, Paradox.
Large metamorphic garnets in an amphibolite.
Looking southwest from the top of Roaring Brook falls, Giant Mountain, Adirondacks.
Reaching the top of Mt. Jo, high peaks in the distance.
Folded calc-silicate layer in marble, banks of the Hudson River.
Summit of Mt. Jo.
View to the southwest, overlooking Monta Rosa.
Nick eating the finest peanut butter sandwich in New Hampshire.
Looking at metamorphosed quartz pebble conglomerate in the Cheshire Quartzite, Pine Cobble Trail, Williamstown, MA.
Jeremy on Littleton Schist, with large sillimanite pseudomorphs after andalusite on the rock surface to the right.
“Billings Fold” just below the summit.
Charnockite gneiss near Schroon Lake.
Lunch on Black Precipice, sitting on the “Seven Sisters” quartzite beds.
Layer truncations against a thick quartzite. Possible pre-metamorphic sedimentary structures, or a fault surface.
Summit of Mt. Jo.
Large plagioclase crystal in a block of anorthosite within the leuconorite, summit of Mt. Jo.
Same as above, with Mike and Bill for scale.
Paying homage to partially recrystallized (Whiteface Mtn. type) anorthosite.
Searching for blue calcite, cascade slide.
Marble-matrix breccia near Paradox.
Fold hinge in one of the isoclinally folded quartzite beds.
End of the trip on the summit of Crag Mountain, on Silurian Clough quartzite which is made out of deformed quartz pebbles and cobbles.
Boulder cave entrance.
Summit of Monadnock.
The Fairy at Fairy Spring, on the Fairy Spring trail to Monta Rosa.
Intrusion breccias and other intrusive features in the roots of the Taconic island arc, Shelburn Falls, Massachusetts.
The largest plagioclase crystal found in this trip, larger than a size 12 boot.
Praying for divine guidance: what is that soft, flakey, metallic mineral in this marble?
Large plagioclase crystal in Mt. Marcy-type anorthosite, Mt. Jo, short trail up.
Folded marble, West Stockbridge Formation, Natural Bridge Park, North Adams, Massachusetts. Photo donated by Ralf Schauer.
Approaching the summit region.
Graded quartzite beds in Littleton Formation schist. Person is standing on the axial surface of an isoclinal fold that repeats the bed, upside down in front and right side up behind.
Summit of Monadnock.
Large garnets in melt pockets in an amphibolite.
Exposures of the Roaring Brook intrusion breccia, Giant Mountain, Adirondacks.
Hornblende needles in muscovite-biotite-chlorite-garnet schist.
The “Billings Fold”, a large isoclinal syncline just below and southwest of the Monadnock summit.