Young geologists who gathered recently at the Munhall Borough Building had a chance to bid on pieces of blue azurite from Morocco, purple fluorite from Kentucky and a boxed set of 24 different minerals from all over South Carolina.
Those items were among a dozen donated specimens offered to collectors at prices as low as 50 cents during a meeting of the Monongahela Rockhounds. The session drew about 35 people, including a dozen children and teenagers.
"You can get into this hobby without breaking the bank," Rockhounds president Tony Orzano, of Baldwin Borough, said. That low financial barrier to entry is one of the factors that makes the hobby attractive.
The 43-year-old club has seen an upsurge in young members and their parents at club meetings.
"We've got amateurs and experts -- little kids and adults who have doctorates," Orzano said.
In addition to its monthly meetings, the Rockhounds organization also sponsors field trips to geological museums and collecting sites, some of which are not ordinarily open to the public. Last month, for example, club members traveled to Flint Ridge Park and Museum, southeast of Newark, Ohio, and to Walworth Quarry, east of Rochester, N.Y.
Rock and mineral collecting seemed a natural fit for Nathan Lunn, his mother Amy said. The 12-year-old always seems to be stuffing his pockets with things he'd found.
A collector for about a year, Nathan reported that the basement of his family's home in Monongahela has been filling up rapidly with specimens. What are his favorites? "I like crystals that fluoresce," he said.
Some minerals, which appear dull in daylight, glow with bright colors when exposed to ultraviolet radiation like that produced by a black light. The property of fluorescence is one of many tests used to identify mineral samples.
The Rockhounds' monthly meetings include the silent auction of mineral samples, a brief talk on a geological subject, and presentation of certificates and badges to young members.
October's meeting topic, for example, was microminerals.
Vice president Bret Howard showed club members magnified images he had taken over the years of items from his collection. They included small emeralds, each less than one-third of an inch, shining flecks of gold on quartz crystals and flower-like manganese oxide dendrites.
If some of the mineralogical language was hard to follow, all of Howard's pictures were striking.
"Sometimes the talks can get technical," Lunn said. "But they try very hard to make it interesting for the kids."
The club is designed to serve the interests of a variety of people, longtime member Dr. Robert Witkowski said. Different members bring different skills to meetings and collecting trips.
"Some know how to do field work, others understand the science," he said.
"We learn a lot here," Nathan Lunn agreed.
Some of the young members said their experience with the club might lead them to possible careers.
"It would be really cool to be a geologist or a scientist and travel the world looking for strange rocks and minerals," said Mallory Zang, 10, of Wilkinsburg. She attends meetings with her mother, Angel.
Many club members are interested in the "lapidary arts," which refers to the techniques involved in cutting and polishing gemstones.
"There's great satisfaction in starting with a rough rock and knowing how to use machinery and tools and skill to transform it into a finished gem," Don Laufer of Canonsburg said.
He works primarily with stones including black onyx, tanzanite, zircons, rubies and sapphires. Like many of the current young Rockhounds, he started out in the hobby at age 12 more than 40 years ago.
Southwestern Pennsylvania is home to at least two other geology-related organizations that include hobbyists.
The Pittsburgh Geological Society meets monthly for dinner and to discuss topics related to the field. The organization has about 300 members and includes many professional geologists and geology students. Its lectures tend to be more technical, according to board member Albert Kollar.
"But we try to reach out to the public with our field trips," he said. "And our talks are open to the public."
Kollar also leads geology field trips sponsored by the Carnegie Museum of Natural History in Oakland. The museum's special-interest group is called PAlS, which stands for "Patrons and lauradanae Supporters." It is named for the trilobite "Ameropiltonia lauradanae," an extinct sea creature related to modern scorpions and shrimp.
PAlS went on its most recent field trip last month. It included stops at Pittsburgh's Calvary Cemetery and Schenley and Frick parks.
Geology as a hobby can satisfy intellectual curiosity about natural history, Kollar said. "It provides an understanding of where we live and why we have the landscape we have -- where the roads are and where the bridges are built."
As a science, the field relies in part on the eyes of observant amateurs to make advancements.
"Many of the discoveries made in paleontology and geology are the result of observations by curious people," he said.