When it was decided that the Gottesman Hall of Planet Earth would be designed around huge rock samples, one obvious choice for the volcano section of the hall was obsidian. This glossy black rock is a dramatic product of volcanism, which is related to plate tectonics. The processes involved in the movement of the Earth's plates, that form ocean basins, build mountains, and cause continents to move and grow, are the same processes that cause volcanism.

Shiny obsidian is unique among volcanic rocks. It cools so quickly when it erupts from a volcano, that there is no time for crystals to form, so it has a smooth, glassy appearance. It is also unusually rich in SiO2, an important component of rocks in general. Obsidian is known as volcanic glass, and although it has a somewhat different make-up than the glass in a window pane its chemical composition is high in silica, just like window glass.

Dr. Ro Kinzler was given the charge of collecting a two-ton obsidian boulder for the exhibition. From her office in New York City, she carefully planned her expedition. First, she organized a meeting with geologist Dr. Julie Donnelly Nolan, a United States Geological Survey (USGS) expert on Medicine Lake Volcano in northeast California. Then, she contacted local pumice quarry owners Glenn and Heidi Malby, who agreed to act as guides. Ro also lined up a videographer and a photographer to document the collection process, and arranged for a flatbed truck to ship the selected specimen across the country.

Years earlier, while working on her master's degree in geology, Ro studied the area around Medicine Lake Volcano, the largest in volume of the Cascade Range volcanoes. The volcano's name came from a lake in its crater, Medicine Lake, which was used by the local tribes.

When Ro thought of a good place to find a large piece of obsidian, she immediately remembered Glass Mountain. This area, part of the Medicine Lake Volcano, was a well-known obsidian site, and had long been used by the local Modoc Indians as a source of the sharp rock for arrowheads and tools. Besides obsidian, the area held a wide variety of other volcanic rock types, ranging in in chemical composition from light-colored, silica-rich rhyolite and shiny black obsidian to black, silica-poor basalt.

Ten obsidian domes, formed during an eruption approximately 860 years ago, rose up to form Glass Mountain, so collecting a large sample appeared to be an easy task. But after spending hours scouring its slopes, accompanied by Julie, Glenn, and Glenn's son Travis, Ro's hopes of finding a giant boulder of obsidian were beginning to fade.

When Ro, Travis, and Glenn scrambled up the domes to inspect the rock, they found that the obsidian was fractured and shattered. Although not unusual for this type of rock, Ro had hoped that by combing through the mounds of obsidian at Glass Mountain, she would be able to find the type of sample she had planned the expedition around.

"Everything was broken and small," she said, finally settling on a rock about 10" by 10" by 24" long. "A nice sample," said Ro. "But not the piece I came out to get."

When Ro drove back to her hotel that night, she began to worry about the feasibility and success of her mission. The next day, as she watched Glenn load another selected volcanic rock, a 300-400 pound boulder of andesite, his wife Heidi Malby sensed Ro's disappointment. She told Ro about a local family, and a collection named "Rockopolis".

Over several years, a local man named Jeff Dinnel had worked part time for the Malbys. Jeff, a self-taught naturalist, had assembled an incredible collection of rocks, bones, and other natural objects from Medicine Lake Volcano. While he often borrowed machinery from the Malbys to bring his samples down from the mountain, other times he moved the large rocks himself with timbers and levers, as the Egyptians did when constructing the pyramids. He arranged his giant rock collection in the yard of his father, Bud, and dubbed the display "Rockopolis."

Shortly before Ro's visit in 1997, Jeff died unexpectedly while Bud was away on a hunting trip. The tragedy stunned not only his family, but everyone in the small surrounding community of Timber Mountain. Ro was struck by the sense of loss and sadness experienced by members of the community when they spoke of Jeff's death. A woman who worked at the Timber Mountain store remembered him vividly. "Jeff was so enthusiastic about things. He loved the volcano so much, and he would come in here and show me rocks that he had just collected."

The Malbys urged Ro to ask Bud Dinnel if she could see Jeff's rock display. When Ro contacted Bud, he invited her over to the house. It was an amazing collection, and Bud graciously said that the museum was welcome to take anything they wanted. In a field across from the house lay a giant boulder of obsidian that weighed almost two tons.

"It was big, glossy, black, and beautiful," said Ro. "I was so happy!" Ro selected not only the huge obsidian boulder from the collection, but a sample of basalt, and four volcanic bombs, blobs of lava blown out of the erupting volcano. "No wonder we couldn't find any good samples of bombs on the volcano," said Ro. "Jeff had already found them all!" This time, when Ro returned to her hotel, she was both elated and pensive. "It was extremely moving to walk through Jeff's collection," she said. "You could tell from the collection that he had grasped what was special about Medicine Lake Volcano." Since the expedition, the Dinnel family and Ro have kept in touch.

"Your visit came when things were very bleak," wrote Jeff's sister, Carolyn Payne. "My brother was a solitary man who held a rich curiosity and respect for all aspects of nature. Most years at Christmas, we never knew if we would get a piece of petrified wood, or petrified clam shells, or an old local bottle that Jeff had dug up. My brother would have been thrilled to know that his treasures will be seen and appreciated by so many people."

Heidi Malby also wrote and spoke for the Timber Mountain community. "What you have done in Jeff's memory has been very healing for all of us." The spectacular boulder of obsidian will be displayed in the volcano section of the Gottesman Hall of Planet Earth. As Ro Kinzler found out during the discovery expedition, an intact obsidian sample of this size is very rare. She and the Museum feel fortunate that the small community of people that live on the flank of Medicine Lake Volcano was willing to share the tragedy and legacy of a man's life. Through this obsidian boulder, the naturalist spirit of Jeff Dinnel will live on at the American Museum of Natural History.