Black Turmeric (Curcuma caesia) is a rare turmeric. It has bluish color rhizome and chocolaty brown when dry. It is also known as kali haldi, Nalla passapu, Black Zedoary, Nar Kachur and Karupu Manjal.
It contains 28% Camphor and smells like camphor. There are many rumor about Black Turmeric burning Camphor Pieces when kept in contact which is false. There are even many videos claiming such activities, however one should not believe in such misleading information and fall into traps of fake item sellers.
(Photos of Black Turmeric can be seen here.)