Interestingly enough, it's from the Times-Picayune.
............Invented by University of Hawaii entomologist Minoru Tamashiro, Basaltic Termite Barrier is made of volcanic rock ground to a precise consistency: 1.7 to 2 millimeters. Granules that size are too big for termites to move, and pack too tightly for termites to penetrate. The gravel must be carefully raked and graded to a uniform 4-inch thickness before a slab is poured over it. BTB is also poured around the foundation. It can cost about $3,000 for an average-sized house. It is not available on the mainland due to the high cost of shipping, though tests have shown granite could be used the same way. .........***