A showy, nearly transparent, colorless, highly unusual and nearly pristine arrowhead twin gypsum crystal from the famous Lake Gilles of South Australia, Australia. This variety is considered to be an extension of the simple swallowtail twin form. A couple of trivial edge bruises certainly do not detract from this strange-looking specimen, whick is partially hollow. The "seed" of the crystal can be seen within. See the Mineralogical Record article in the May-June, 1982 issue, Vol. 13, No. 3. Ex Marty Lewadny Collection of Winnipeg, Canada. 6.9 x 6.8 x 4.4 cm