Basalt rhymes with:
assault, assault, salt, sault, assault, ault, brault, covault, dault, default, exalt, fault, galt, gault, halt, kalt, kuralt, malt, mault, nault, pinault, salt, sault, vault, walt
Basalt sounds like:
backslide, basaldua, basulto, beguiled, bezold, bicycled, bisexuality, bobsled, boggled, booklet, buccellato, buchwald, buckled, busload