117 



form, in a few places, a layer 

 of several centimetres in thick- 

 ness. The quartz layer is some- 

 times deposited on the stilbite 

 crystals themselves. The length 

 of the stilbite crystals is from 

 3 — 4 cm. and they fill the grea- 

 ter part of the centre of the 

 cavities. They are flattened 

 parallel to Ь (OIO) and show the 

 combination: r{00l}, 6{010}, 

 e {oil}, m {по} and t {l30} 



(Fig. 5). The last mentioned form is rare in stilbite 

 occurs very commonly here. It is determined thus : 



Fig. 5. Stilbite; 

 Henry Land. 



but 



Average Variations ^"'«ber of Calculated 



value measurements value 



^:è = (130):(010) = 28°53' 27°40'— 29°53' 4 29°Ô2V2' 



The accuracy of the calculation is very close, considering 

 that stilbite, on account of its curved faces is, as a rule, 

 not at all well adopted for measurements. The crystals are 

 of a light reddish colour and slightly transparent. 



3) On the beach, at the foot of Mount Henry, stilbite crystals 

 have been found. They cover the walls of a fissure in grey 

 basalt. The crystals are covered, especially on one of sides, 

 with a layer of rounded, grey, calcite crystals. The stilbite 

 crystals are about 5™°i long; their form is rather broad with 

 r{00l} about as large as ô{010}; ш{П0} and /"{Toi} are 

 also found. The surfaces of the crystals are cloudy and 

 of a brownish colour; the inner part is whitish and semi- 

 transparent. 



4) From the hot spring some rather small stilbite crystals of 

 the ordinary flattened form were obtained, in association 

 with small spherical masses of thomsonite. 



