Hydrofluoric acid is a gas extraction stimulation fluid:
– http://www.onemine.org/search/summary.cfm/ProducingEquipment-Methods-and-Materials–Hydrofluoric-Acid-Stimulation-of-Sandstone Reservoirs?d=305ECAF73DBA21C942E1F42B94FBA2CC8919EC34772E7F46B2154E42EC8AF57526874
All lanes on Route 33 now open; truck with hazardous spill has been cleaned up
http://www.poconorecord.com/apps/pbcs.dll/article?AID=/20090321/NEWS/90321002/-1/NEWS01

Aerial photo of tanker on its side on Route 33 this morning, slowly leaking hydrofluoric acid. The area has been evacuated.
David Kidwell/Pocono Record
March 21, 2009
All lanes are now open on Route 33 South.
Route 33 was closed in both directions from Saylorsburg exit to below Wind Gap. Officials removed an overturned tractor trailer carrying a hazardous chemical.
A leaking valve has been repaired and crews had to safely upright the truck and remove it, said Guy Miller, Monroe County emergency services director.
The truck wrecked at about 3 a.m. this morning between ½ and 3/4 mile south of the county line.
Northampton County spokesman John Conklin says the truck driver was treated for injuries and released. There were no other immediate reports of injuries.
Conklin says hazardous materials teams managed to stop the slowly dripping liquid. He says not enough of the chemical leaked to create a toxic cloud.
Hydrofluoric acid in low doses can irritate the eyes, nose, and respiratory tract. Inhalation can be fatal.