142 î'. SCMEÎ. 



nite. The largest crystal measures 28 millimeters across and 

 such measuring 10—15 millimeters are common. 



3. Albite in pseudomorphs after laumontite from 

 Landsværk, Evje. 



In the pegmatite mass of Landsværk cavities and fissures 

 are found, often empty, but not seldom filled with an earthy 

 substance consisting of chloritic minerals with some kaolinite. 

 In this mass lie embedded crystals of quartz with both ends 

 bounded by well developed faces; others only protrude in the 

 chloritic mass, having formed on the wall of the cavity. 



On some of these quartzes and especially on a piece of 

 feldspar, belonging to the pegmatite itself, some 20 centimeters 

 high and broad and projecting in the cavity, numerous pseudo- 

 morphs were observed. 



Prismatic crystals, implanted on the quartz and feldspar, 

 have been coated, together with the first named minerals, with 

 a thin layer of pale red to colour less albite in small tabular 

 crystalls, showing a few broad twinning lamellæ; then the sub- 

 stance of the prisms has been carried away, and has left a 

 mould, which has sometimes been partially filled with the same 

 light coloured tabular albite. The length of the prisms has 

 been up to 30 millimeters by at thickness of 5 — 8 millimeters. 

 (Fig. 5.) 



The angles of the prisms have been measured with the 

 hand goniometer and were found about 95° resp. 85° — 87°. At 

 the free end, an oblique face is invariably seen, whose angle 

 against the acute prismatic edge was observed to be near to 55°. 



The angles and the habit agree with the common type of 

 laumontite. 



As similar pseudomorphs, though of orthoclase were descri- 

 bed long ago, and unaltered laumontite was often observed in 

 syenitic and granitic rocks, the original mineral may well be 



