Cleavage, pretty distinct parallel to the broad faces of 

 the crystals, or the shorter diagonal of the prism. Surface 

 deeply striated lengthwise of the prism. 



Lustre adamantine. Color, various shades of brown ; of 

 which yellowish brown, hair-brown, clove-brown and black- 

 ish brown, are the most common. Streak yellowish brown. 

 Crystals often semi-transparent, and showing a blood red 

 tint. Other varieties are nearly opake. 



Brittle. No action on the magnet. Hardness =5*0. .. 

 5*5. Sp. gr. == 3*922, of a columnar, compound variety. 



Compound Varieties. Globular, reniform, stalactitic 

 and fructtcose shapes : surface, of various descriptions, 

 smooth, granulated, reniform, drusy ; composiiion colum- 

 nar, individuals very delicate, often impalpable. In tho 

 latter case, fracture becomes even, flat conchoidal, or un- 

 even. The composition is often repeated ; granular and 

 curved lamellar masses are formed of columnar composi- 

 tions, the faces of composition oeing either smooth, or cov- 

 ered with reniform asperities. Massive : composition co- 

 lumnar or impalpable. Sometimes the particles are so 

 slightly coherent, that the mass appears earthy and dull. 

 Pseudomorphoses of Calcareous Spar. 



1. The present is one of those species in mineralogy, which, on ac- 

 count of the varieties in regard to composition, and the intermixture of 

 other species, has been treated of under a great diversity of names, as 



VOL. II. 2 



