How a Love of Herkimer Diamonds Led to Volcanoes and Earthquakes

Dr. John Tacinelli recalls finding a Herkimer Diamond in his grandmother’s driveway as a child. It was pointed at each end – a rarity, as they’re usually pointed on just one end. As a young boy, the stone, which is actually a quartz crystal, captivated him.

“It all started with a crystal,” Tacinelli says simply. “They’re the local equivalent of agates. I spent the rest of the day combing through the driveway for more.”


John Tacinelli.

Tacinelli’s father would eventually bring him to the quarry where they were extracted.

“Every time we visited my grandma we’d walk up and down these big piles of gravel and find little bits and pieces of these Herkimer Diamonds,” he recalls. “Then he got the idea to go to the abandoned quarry and we started finding all sorts of cool crystals in there. It just kind of sparked an interest in minerals, mineralogy, fossils.”

The allure of the water-clear quartz eventually led to Tacinelli’s current position as a science instructor at Rochester Community and Technical College (RCTC), a position he has held for 20 years.

He has four degrees in Geology, culminating in a Ph.D. from the University of Minnesota. He began his academic career by earning his A.S. from Dutchess Community College in New York, B.S. from State University of New York at Stony Brook, and M.A. from Binghamton University in New York.

His academic endeavors have led him all over the world – including Iceland, Greenland, Scotland, Hawaii, and Costa Rica – to study rocks. What the igneous petrologist specifically was interested in was igneous rock, a byproduct of cooling volcano magma.

Eventually he became interested in earthquakes (even teaching a popular volcanoes and earthquakes class at RCTC), and the college has a cool device on campus to measure them all around the world: a seismograph.

The seismograph, or seismometer, sits underneath the Charles E. Hill Theater, and it detects earthquakes and other seismic events locally, but also as far away as Japan.

“It’s one of the things our students study,” says Tacinelli. “They can look at earthquake events as they’re happening. In some cases, we’ve even had them happen during lab while looking at the seismograph (readings).”

TacinelliSideBarMore recently the device picked up an explosion at a Silica Sand mine near Mankato. Sure enough, the machine has been picking up many mine explosions over the years. Students, and anyone who visits this link, can look at the last 24 hours of activity.

“We have a pretty continuous record going back to 2009,” Tacinelli says of the data that is archived, though sometimes the machine goes offline and is not able to record data that day.

Some of the more interesting, and devastating, data comes from the 2011 Tōhoku earthquake in Japan. More recent data sets come from earthquakes in Oklahoma tied to the disposal of waste water from the oil and gas industry, and April’s quarry blast in the Mankato area.

“It led to the realization that we’ve probably been picking up other quarry blasts from the area,” says Tacinelli, which is indeed the case. Someone who works at an engineering firm investigating the quarry blast has even asked for the seismograph data that RCTC has collected.

It’s quite the culmination of Tacinelli’s Rochester adventure, one that began so many years ago during a – no surprises here – Minnesota winter.

RCTC seismograph.

RCTC seismograph.

“Two months after I arrived in Minnesota we had this giant blizzard, the famous Halloween blizzard of ’91. My back still hurts from shoveling that snow,” Tacinelli quips.

“It’s been a great school and I’ve had a good time teaching,” Tacinelli notes shortly after.

RCTC’s igneous rock and earthquake guru isn’t sure if he still has his Herkimer Diamond he found years ago at his grandmother’s.

But that’s OK.

He’s gathered plenty of other “gems” since then (they aren’t fun to travel with he notes). Some of them are even on display on the second floor of Science and Technology.

“I still have a pretty nice collection of quartz crystals from that area,” Tacinelli says.

And he is still collecting rocks and fossils years later, never losing that curiosity and excitement.

“My hobby is kind of my job.”

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