Kilbourne’s Volcanic Confetti

(Close-up of olivine. Photo: Katherine Wright)

By Kayla McKiski

Christine Knudson, a research assistant at NASA Goddard Space Flight Center, handed me the sparkling rock resting on a gridded page of her field journal.

“This is olivine,” Knudson said, pointing to the coarse green crystals. “This is where the gemstone peridot comes from.”

These spectacular rock-coated, olive-colored minerals decorate the land around Kilbourne Hole. One of the most abundant minerals on the planet, it originated miles below the earth’s crust, deep in the second layer, the mantle.

The water-driven volcanic eruption of Kilbourne 24,000 years ago ripped these crystals from the mantle, coating them with lava, like fondue, as they exited. The lava cooled around them, creating shells of the igneous rock basalt.

Spewed around the crater after the explosion, these rocks are called “xenoliths,” a volcanic confetti of sorts.

The area may be sprinkled with potential gemstones, but droves of people are not kicking it into four-wheel drive to get rich from Kilbourne. “Most people don’t know that this is here,” Valeria Martinez, a Ph.D. student studying geology at the University of Texas at El Paso, said. “It’s also very hard to find a sample with good color, clarity and size.”

Hard but not impossible. We started searching the vicinity for gemstone-quality olivine but came up empty. “They’re very difficult to find,” Martinez confirmed, laughing. “I’ve only found a few and I’ve looked many, many times.”

After I gave up on finding gemstones Knudson walked over to me again. This time she placed a foliated, gray scale rock in my hands.

“This one’s nice,” Knudson said.

“But what is it?” I asked.

“It’s gneiss,” she said, smiling at her geology pun.

I laughed and took another look.

Gneiss was nice but I liked the volcanic confetti better.

(Close-up of olivine. Photo: Katherine Wright)

By Kayla McKiski

Christine Knudson, a research assistant at NASA Goddard Space Flight Center, handed me the sparkling rock resting on a gridded page of her field journal.

“This is olivine,” Knudson said, pointing to the coarse green crystals. “This is where the gemstone peridot comes from.”

These spectacular rock-coated, olive-colored minerals decorate the land around Kilbourne Hole. One of the most abundant minerals on the planet, it originated miles below the earth’s crust, deep in the second layer, the mantle.

The water-driven volcanic eruption of Kilbourne 24,000 years ago ripped these crystals from the mantle, coating them with lava, like fondue, as they exited. The lava cooled around them, creating shells of the igneous rock basalt.

Spewed around the crater after the explosion, these rocks are called “xenoliths,” a volcanic confetti of sorts.

The area may be sprinkled with potential gemstones, but droves of people are not kicking it into four-wheel drive to get rich from Kilbourne. “Most people don’t know that this is here,” Valeria Martinez, a Ph.D. student studying geology at the University of Texas at El Paso, said. “It’s also very hard to find a sample with good color, clarity and size.”

Hard but not impossible. We started searching the vicinity for gemstone-quality olivine but came up empty. “They’re very difficult to find,” Martinez confirmed, laughing. “I’ve only found a few and I’ve looked many, many times.”

After I gave up on finding gemstones Knudson walked over to me again. This time she placed a foliated, gray scale rock in my hands.

“This one’s nice,” Knudson said.

“But what is it?” I asked.

“It’s gneiss,” she said, smiling at her geology pun.

I laughed and took another look.

Gneiss was nice but I liked the volcanic confetti better.