School officials say they simply erred on the side of caution when they evacuated a high school because a rock caused a radiation detector to crackle wildly, sending a classroom into a panic.
"We did not know what we had in that classroom," schools Superintendent Lee Seitz said Wednesday.Earth science teacher Rita English was demonstrating the Geiger counter this week at Colonia High School with small store-bought samples, then tried it out on some rocks in a storage cabinet.
"She touched some small rocks, and it made little `click, click' noises," said Tyrona Timmons, 15. "Then she brought out this big rock, and when she touched it, it started beeping real loud."
The school was evacuated 90 minutes later, and a hazardous materials team clad in lead aprons borrowed from a dentist secured the grapefruit-size chunk of rock in a lead-lined box.
Classes were canceled so the school could be tested for radiation contamination. No abnormal readings were detected, but the classroom and a hallway were wiped down as a precaution.
The rock was identified as a chunk of pegmatite coated with autunite, a uranium calcium phosphate that is radioactive.
"The levels are so low according to (environmental) officials that you're more likely to get more radiation from your smoke detector in your house than you would from this rock," Seitz said.
But no one knew that when the Geiger counter went off.
"They took precautionary measures," said William Csaszar, a radiation physicist for the state Department of Environmental Protection "They didn't know what it was, and you can't fault them."
Geiger counters, Csaszar said, are "very sensitive detectors."
Gerald DeMenna, a scientist with Chem-Chek Corp. in Pis-ca-ta-way, tested the rock and said the radioactivity coming from the autunite was 10 times less than what a person would be subjected to sitting in a doctor's office where X-rays were being taken.
Parents of about 70 students who were in the classroom Tuesday afternoon were notified and advised to have their children bathed. It was also suggested the students' clothes be washed immediately and the bottoms of their shoes wiped clean.
"It will be a lesson they'll never forget," Seitz said.