Dunno them either! Now black jack gum, that's good stuff.
Are they hard wood? Most hard woods (or fruit wood, or nut wood) are ok, I think.
Could always burn some and smell it...!
On edit, is it a blackjack oak? If so...bet it's fine!
GENERAL BOTANICAL CHARACTERISTICS :
Blackjack oak is a small to medium-sized, slow-growing, native,
deciduous tree. It is often shrubby with a low, rounded crown. The
contorted, down-sweeping branches remain on the tree several years after
they die [46]. Leaves are tenacious after having turned brown, often
clinging to the tree throughout the winter [50]. The acorns are about
0.4 inches (1 cm) long [41]. On poor xeric sites or in drier climates,
blackjack oak is rarely taller than 30 feet (9 m) [49,50]. On better
sites, it grows 45 to 50 feet (14-15 m) in height [15,49]. Blackjack
oak has lived to be as old as 230 years in Oklahoma [23].