32 MR W. F. P. M'LTNTOCK ON THE ZEOLITES AND ASSOCIATED MINERALS 



Plate II. 



Fig. 1. Ophitic Basalt [1 1 4] with Vesicle, magnified 27 diameters. — The dark area at the foot is the rock 

 showing the outline of the vesicle. The light-coloured area filling up the hollows at the junction is a mixture 

 of purple augite, magnetite, and prelmite. This is succeeded by a zone consisting of turbid albite, at the left 

 towards the top; irregular patches of epidote, just above the centre; augite, in idiomorphic, lath-shaped 

 crystals ; and prelmite enclosing chlorite, which shows white in the photograph. A large augite crystal is 

 seen at the top, on the left, projecting into albite ; others, associated with magnetite, are seen on the right 

 towards the top. Maol nan Daruh, Ben More, Mull. 



Fig. 2. Ophitic Basalt [109] with Vein, magnified 19 diameters. — The rock at the foot is succeeded by a 

 layer consisting of large crystals of augite, one of which lies with its axis parallel to the wall of the vein, 

 magnetite, albite, and chlorite. Above this is turbid albite which, at the top, towards the right, is succeeded 

 by scolecite enclosing corroded scraps of epidote. Maol nan Damh, Ben More, Mull. 



Fig. 3. Amygdale [1 1 3] in Ophitic Basalt, magnified 27 diameters. — The clear white material is scolecite. 

 In the centre is a large, dissected crystal of epidote consisting of four fragments. The first is the irregular 

 patch with tufted margins in the centre ; the second is the rhomboidal piece lying directly beneath ; 

 the third lies immediately to the right of the second ; and the fourth lies above the third. The four frag- 

 ments have their cleavages parallel and extinguish simultaneously. The spaces between them are filled with 

 scolecite enclosing rectangular turbid crystals of albite, in the centre and to the left connecting the third and 

 fourth fragments of epidote. Near the foot on the left a turbid albite is in process of being replaced by 

 scolecite. The dark areas at the left and right margins are epidote ; beneath the latter one is a corroded albite. 

 Maol nan Damh, Ben More, Mull. 



Fig. 4. Ophitic Basalt [104] with Vesicles, magnified 27 diameters. — The small vesicle underneath is 

 filled with analcite replacsd by granular albite. The dark patches are chlorite moulded upon the analcite, 

 and the long lath-shaped crystals which lie round the junction and also pierce the analcite are purple augite. 

 A large one projects through the orifice connecting the small vesicle with the overlying main one. This 

 vesicle is filled with a layer of augite, magnetite, and albite, seen on the right of the canal between the two 

 vesicles ; chlorite, forming the dark patch on the left ; and albite, pseudomorphous after analcite, at the top. 

 Maol nan Damh, Ben More, Mull. 



Fig. 5. Ophitic Basalt [78] with Vesicle, magnified 27 diameters. — The dark area to the left is the rock. 

 At the junction with the vesicle is a thin layer of garnet with little rounded and dissected masses isolated 

 from the layer. Near the top is a projecting knob of garnet in process of dissection. Overlying the garnet 

 is a mixture of scolecite and heulandite enclosing laths of diopside and epidote. The dark bar consists of 

 diopside, showing signs of corrosion, and a dull birefringent material similar to that which surrounds much 

 of the corroded garnet. The dark crystal on the right is a corroded piece of epidote. Maol nan Damh, Ben 

 More, Mull. 



Fig. 6. Metamorphosed Amygdale [17], magnified 27 diameters. — The amygdale is filled with scolecite 

 showing incipient turbidity. Traversing the scolecite are crystals of epidote with yellow primary cores, 

 enclosing chlorite and showing the original corroded outlines, and secondary, colourless rims. North-east 

 slope of An Gearna, Ben More, Mull. 



Plate III. 



Fig. 1. Metamorphosed Amygdale [49], magnified 27 diameters. — The turbid patch on the extreme left 

 and the two areas extending from the top and bottom respectively towards the centre are scolecite in process 

 of replacement by prehnite, which forms the white areas in the photograph and, in the case of the upper and 

 lower central masses of zeolite, forms little fibres traversing and replacing scolecite. The dark crystals to the 

 left of the central zeolite are garnet, the one near the centre showing a core of secondary prehnite. The 

 fibrous crystals, on the right towards the foot, are secondary epidote traversing secondary prehnite. Beinn 

 Fhada, north end, east side, below the summit, Mull. 



Fig. 2. Metamorphosed Amygdale [58], magnified 27 diameters. — The turbid fibrous material, extending 

 from the right towards the centre and forming the area at the bottom towards the left, is scolecite in process 

 of replacement by prehnite, which forms the white areas. The mass of prehnite extending from the centre 



