Min. [ad. G. synadelphit (Sjögren, 1884), f. Gr. σύν SYN- + ἀδελφός brother + -it, -ITE1: so named ‘because intimately associated with other related species’ (Dana).] An arsenate of manganese and aluminium, with some calcium and magnesium, occurring in black or brownish-black monoclinic crystals.
1892. Dana, Syst. Min., 801.
