131 



The lorenzenite crystals belong to the riiombic system. 

 From the angles 



(120): (120) = 100° 47' and (lll):(llO) = 55° 13', 



determined by fairly accurate measurements, are calculated the 

 I'ollowing axial ratios : 



a:b:c = 0,6042 : 1 : 0,3592. 



Referred to these axial ratios tlie forms present have the 

 following symbols: 



a = {lOO}, b == {OlO}, m. = {lio}, и = {l20}, 

 X = {l. I2.0}, 2^ = {m}, = {23l}. 



The first pinacoid is of rare occurrence, and its planes 

 are extremely narrow. The second pinacoid occurs less rarely, 

 and its faces are sometimes tolerably wide. They are often 

 striated parallel to their longitudinal direction. The prism of 

 the third order, m, occurs on the majority of the crystals, 

 but its faces are generally narrow. The particularly dominating 

 form on the lorenzenite crystals is the prism of the third 

 order, n, which is always present, often with its faces so 

 broad, that the other faces in the vertical zone, compared 

 with them , are exceedingly small. The rather remarkable 

 form X is of frequent occurrence, and its faces are gene- 

 rally rather broad. The I'orm x and the second pinacoid 

 seem, as it луеге, to replace one another, for on crystals on 

 which the pinacoid occurs, the former is in most cases absent 

 and vice versa. The faces in the vertical zone are often 

 striated parallel to their zonal axis, so that in this zone accu- 

 rate measurements can seldom be obtained. Exceptionally the 

 crystals have even faces, those of the form n being always 

 the most perfect. The termination of the crystals always 

 consists of the bipyramid 79, and on some crystals, also the 

 bipyramidal form 0. The faces belonging to the form p are 



9* 



