Thanks to Tom Loomis of Dakota Matrix Minerals, Inc., for the picture of the ~ 1 cm long, X-ray verified specimen.
Rossmanite was found in a lepidolite subtype pegmatite dike at Dobra Voda. It occurs with other members of the tourmaline group (schorl and elbaite). Based on paragenesis and textural relations, elbaite-rossmanite is the last tourmaline to crystallize at Dobra Voda.
Composition:
References:
Selway JB, Novák M, Cerný P, Hawthorne FC (1999) Compositional evolution of tourmaline in lepidolite-subtype pegmatites. European Journal of Mineralogy, 11:569-584.
Novak
M, Stanek J (1999) Lepidolitovy pegmatit od Dobre Vody u Velkeho
Mezirici, zapadni Morava. Acta Musei Moraviae. Scientiae Geologicae.
Casopis Moravskeho Muzea 84, 3-44.