This mineral appears to be known from only one specimen, which was in La Metherie’s collection, and passed along with it into the hands of Mr. Heüland. Having free access to the rarities in this gentleman’s possession, I have taken an early opportunity of making known the general appearance of an unique specimen, leaving the more minute detail to one or two friends who have commenced the investigation, and who will I hope obtain some knowledge of its composition, and favour the world with the result of their labours. In the mean time the following observations may serve to assist the figure:—It has much of the aspect of white tremolite, but is more compact, and in shorter bars. The crystals are thick prisms of six, eight, or more sides: four of the sides are larger than the rest, and so placed, that if alone they would form a prism of about 87 and 93 degrees: this prism is divisible with ease in the direction of its short diagonal, producing a brilliant face, and is also foliated parallel to two of its sides: the cross fracture is between conchoidal and hackley: it possesses various degrees of transparency, with a low degree of lustre: it yields with difficulty to the edge of a knife, dividing into fibres mixed with powder. One of the crystals exposes two terminal faces, inclined upon that face of the prism parallel to which the crystal is foliated: these, if accurately measured, may lead to the knowledge of the integrant molecule. The specimen is from Capo di Bové, near Rome.