Rossmanite was found in a lepidolite subtype pegmatite dike at Laštovicky. It occurs as pale-pink, 1.0 cm crystals in lepidolite 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 Laštovicky.

Composition:

([]_0.59Na_0.41) (Li_1.15Al_1.85) Al₆ (Si_5.89Al_0.11O₁₈) (BO₃)₃ [(OH)_3.89F_0.11]

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.