Answer :

The answer to the question is no, you can’t expect to find
black sand beaches on Kauai, it is because black sand beaches are only found on
islands that are recently have been formed from the black larva that has been
breakdown from the volcanoes that had been erupted and Kauai is not included.
You can only expect to find at this island is white and yellow sand beaches.

Black sand beaches are expected on Kauai because of the local volcanic rock composed of basalt, which produces mafic minerals upon erosion. In addition to black sand, green sand composed of olivine is also present due to similar geological processes.

Yes, one would expect to find black sand beaches on Kauai due to the weathering of local volcanic rock. Kauai, like other parts of Hawaii, has an abundant source of basaltic rock, which over time erodes under weather and wave action to form black sand beaches. The black sands are rich in mafic minerals, which derive from the local basaltic lava and can be more easily broken down compared to clasts of felsic minerals like quartz.

Furthermore, it's not only black sand that can be found in Hawaii. The islands are also home to green sand beaches composed of semi-precious olivine crystals that have eroded from basaltic rocks. Beaches can be comprised of various substrates depending on the local geology. For instance, the sand in Hawaii ranges from white coral sands to the unique black and green volcanic varieties. This diversity in beach substrate is due to the different types of sediment that are dominant in each locality.