What do you think the object on the left has in common with the three objects on the right? This question isn’t too hard to answer: they’re all fossilized clams. But why do they look so different?
The clam on the left is the mineralized shell of a clam from Coal Creek, Washington. After the clam died, its shell was encased in sedimentary rock; while that rock was forming, foreign minerals grew and replaced the original calcium carbonate the shell was created from when the clam was alive. (These replacement minerals are responsible for the dark color.)
The clams on the right, on the other hand, are agate molds of clam shell insides. They come from Green Creek in Washington. Their tops have been polished a bit to give them a nice shine, but the shapes are natural. After these clams died, agate filled in the insides of their shells, and the shells themselves dissolved away.
These fossil clams show just two of the many different modes of fossil preservation!
OPB Radio reported on the amazing archaeological discover of a knife carved from agate currently estimated from 15,000 years ago in Eastern Oregon, evidence of what could be the oldest human occupation west of the Rocky Mountains, shaking up many theories on North American human history.
Carved from clear orange agate, the stone knife has been described as a Swiss Army Knife of its day with a serrated point edge like a saw and a steep, flaked edge used to carve wood and scrape hides and cut meat from the bones of prey. Blood found on the stone has been tested and found to be Bison antiques, an ancient ancestor of the modern bison or buffalo in North America. Continue reading →
Julian Gray and Leslie Moclock with the Rice NW Museum case of agates at the 2014 Denver Gem & Mineral Show. This case won the Donna Chirnside Memorial Award for best educational case by a museum.
Thousands of people attended the Denver Gem & Mineral Show held the second weekend in September each year in Denver, Colorado. The theme of this year’s show was near and dear to the heart of the Rice NW Museum and Oregonians rockhounds: Agate. Agates are found in many places in Oregon and are well represented in the Rice NW Museum’s permanent exhibits. Curator Leslie Moclock selected about two dozen of the best agates and thundereggs from the museum’s collection for two temporary educational exhibits at the show September 12-14, 2014. Taking the museum to mineral collectors in attendance at shows is part of the museum’s outreach program.
Both exhibit cases were recognized for their excellence in educational content and quality of exhibition. The Denver Gem & Mineral Show Committee selected the Rice NW Museum’s case on the origin of agates for the Donna Chirnside Memorial Award honoring the best display by an institution at the show. The Friends of Mineralogy, a group that promotes mineral education, awarded the Best Educational Case by an Institution Award to the Rice NW Museum case featuring thundereggs, Oregon’s State Rock.