What is "thunderegg"

n. A roughly spherical, nodule-like geological structure, similar to a geode, that is formed within a rhyolitic lava flow.

A thunderegg (or thunder egg) is a nodule-like rock, similar to a filled geode, that is formed within rhyolitic volcanic ash layers. Thundereggs are rough spheres, most about the size of a baseball—though they can range from less than an inch to over a meter across. They usually contain centres of chalcedony which may have been fractured followed by deposition of agate, jasper or opal, either uniquely or in combination. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions. Thundereggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colours. A characteristic feature of thundereggs is that (like other agates) the individual beds they come from can vary in appearance, though they can maintain a certain specific identity within them.

Thunderegg is not synonymous with either geode or agate. A geode is a simple term for a rock with a hollow in it, often with crystal formation/growth. A thunderegg on the other hand is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it (see illustration of Gehlberg specimen), but not all geodes are thundereggs because there are many different ways for a hollow to form. Similarly, a thunderegg is just one of the forms that agate can assume.

Thunderegg is an American rock and roll band and recording project currently based in San Francisco, California, led by songwriter Will Georgantas (guitar, vocals) and including Reese Douglas (guitar), Alex Jimenez (bass, vocals), and André Custodio (drums). Its earliest incarnation was the Yale University band Larry, formed in 1992 and featuring founding Thunderegg players Jake Fournier (bass) and Keith Woodfin (drums).

Between 1995 and 2004, Georgantas recorded the first eight Thunderegg albums by himself to four-track cassette in various apartments in Brooklyn, New York, and his parents' house in Princeton, New Jersey. These albums, from 1995's Universal Nut through 2004's Sweetest One, display increasingly elaborate lo-fi (or "bedroom music") arrangements, and reviewers have remarked on their high lyrical quality. In January 2006, all of these recordings were collected for the anthology Open Book: The Collected Thunderegg, 1995–2004. The independently produced Open Book featured 231 mp3s on a single data CD along with a 108-page illustrated lyric book. It enjoyed a positive reception both for its large scale and its music, which was likened to rock in the vein of Guided by Voices, The Velvet Teen, and The Mountain Goats.

Thunderegg began playing and recording as a full band in 2000 after Fournier moved back east to Hartford, Connecticut, from Portland, Oregon. (The band was named after the thunderegg, the state rock of Oregon.) In 2002 a new full-band version of Georgantas's song "If I Went on a Diet" was selected for inclusion on a compilation CD produced by Jane magazine; in 2005 that song and nine others would comprise Thunderegg's first full-band album, A Very Fine Sample of What's Available at the Mine. Thunderegg's second full-band album, Line Line, would be produced and mixed by Alan Weatherhead ( Sparklehorse, Cracker) at Sound of Music Studios in Richmond, Virginia, and released independently in September 2011. A follow-up with Weatherhead, C'mon Thunder, featuring Darren Jessee of Hotel Lights, was released on May 13, 2014, to positive critical reception.

Throughout, Georgantas continued to record at home on a 424 Portastudio: In 2005 he posted a new song every week to Thunderegg's website, the best of which were collected for the CD This Week, which was self-released in early 2007. Several other albums followed, including Not What I Meant, Thunderegg's first San Francisco album, which was recommended for fans of " The Eels, Ween, The Flaming Lips, and Pulp." That album's closing track, "The Guest Star of the Rest Stop," was initially commissioned by author T Cooper for a CD accompanying his 2012 book Real Man Adventures.

Thunderegg toured Germany in the summer of 2013 with a lineup that included Georgantas, Fournier, Moon, and Ken Matsuda (violin), and Georgantas toured the United States (with KC Turner) in summer 2014. In April 2015 the band released the seven-inch single "Ten Sleeves"/"Big Cigarette," again recorded with Weatherhead, this time with the California lineup at Tiny Telephone in San Francisco.