ie ee ae 
optical methods. In order to show their relations to 
1891.] Mineralogy and Petrography. 141 
Correcting for the small amount of calcite present, the analysis cor- 
responds with the formula (48; Ca, 745 Mn), Na H (SiO,),—a pectolite 
with a tenth of its calcium replaced by manganese.- In its optical 
properties the new mineral agrees well with the view that it is closely 
allied to pectolite. Its axial plane is Po, With ò the acute 
bisectrix. The double refraction is positive, and the dispersion 
is strong s> p. Pinakiolite and trimerite are both new miner- 
als from the Manganese Mines in Sweden. The name of the first 
refers to its occurrence in small, tabular crystals. It was found by 
Flink ê in granular dolomite at Langbanshyttan, associated with haus- 
mannite. The density of the new mineral is 3.881, and its hardness 
is 6. It is soluble in strong hydrochloric acid with evolution of 
chlorine, and before the blowpipe it fuses with difficulty to a black 
bead. An analysis of the hydrochloric acid solution yielded : : 
BO, MgO Mn,O, - FeO,” CaO PbO SiO, H,O 
15.65 28.58 49-39 2.07, 1.09. A0 1,28 +47 
Correcting for silica and water, the formula becomes R,BMnQ,, or a 
manganese /udwigite. The black, lustrous crystals are usually ortho- 
rhombic, rectangular tables, in which the brachypinacoid is most 
developed. In addition to this there is present in the mineral only 
» P3. A definite termination of the ¢ axis is lacking, but since twins 
with a brachydome as a twinning plane are common, the axial ratio 
was calculated with this as the unit form, and the following result ob- 
tained: a: 6: c—=.83385: 1: -58807 Cleavage is parallel to 
»Po- The optical axial plane is oP, with å the negative acute bisec- 
trix. The absorption is B> 4> C, with B= ¢ = opaque ; A=b= 
reddish-brown, and C= a = reddish-yellow. 7) rimerite (tprp phs = 
three-fold) was found at the Harstigsgrube associated with friedelite 
etc. The density — 3.474, and hardness = 6-7. The pulverized 
mineral dissolves in hot hydrochloric acid, with the separation of 
gelatinous silica. Its composition : 
SiO, BO MnO FeO CaO MgO 
39.77 17.08 26.86 3-87 12-44 61 
corresponds to (MnBe)SiO,, a manganese phenacite. The tans 
parent bright red crystals have an hexagonal habit, due to twinning of 
triclinic individuals, whose triclinic nature is discoverable only by 
the Willemite 
® Zeits. f. Kryst., XVIIL., 1890, p. 361. 
