One of the rock enthusiasts on Nyssa's Thunderegg Days rockhound tour split open a seemingly simple rock to find an agate. Each ring in the agate indicates a different "blurb" of water carrying various minerals that affect the color, according to rock tour leader William Nance. (The Enterprise/Isabella Garcia)

NYSSA — Nyssa's three-day Thunderegg Days celebration is full of community events, local vendors and, for those who want to explore off the beaten path, rockhound tours.

While thundereggs, a type of rock formation made exclusively through rhyolite lava, are abundant in the hills surrounding Nyssa, tour-goers can find opal, agate and other colorful mineral deposits. The first of two rockhound tours, led by archeologist and geologist William Nance, attracted a small group of six rock enthusiasts to rhyolite lava calderas and beach strands in the ancient Idaho lake area. Though the drive was bumpy and the sun was hot, the gleaming stones were highly rewarding.

The last Thunderegg Days rockhound tour will leave from the Nyssa Elementary School parking lot at 7 a.m. Saturday, July 13. 

Tour guide William Nance, an archeologist, indicates promising land to dig for gems. (The Enterprise/Isabella Garcia)

William Nance educates the tour-goers on what to look for among the dirty and brush. (The Enterprise/Isabella Garcia)

Nance explains that pieces of agate like this take 14 million years to form. (The Enterprise/Isabella Garcia)

Experienced rock hound Neil Potts identifies a vein—a crack that has significant mineral deposits due to water flow—of material and alerts the group. (The Enterprise/Isabella Garcia)

While experienced rock hounds can spot promising rocks in nearly any condition, it's easier to tell if you've hit a deposit once the rock is cleaned off. (The Enterprise/Isabella Garcia)

William Nance guides attendees on what indicators to look for on the surface of a rock to find gleaming interiors. (The Enterprise/Isabella Garcia)

A vein proves fruitful for the group, providing plenty of pale green material that can be made into jewelry or beautiful polished stone. (The Enterprise/Isabella Garcia)

John Wasden, from Boise, digs out some promising pieces. (The Enterprise/Isabella Garcia)

Back at the Nyssa Elementary School, Wasden finds a festival vendor to cut some of the Jasper he found on the tour. (The Enterprise/Isabella Garcia)

The cut Jasper reveals a beautiful crosshatch, a promising start for a piece of jewelry or cool rock for his grandkids. (The Enterprise/Isabella Garcia)

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