380 Transactions. — Geology. 



2. Crystals of Barytes. — Thames. A very interesting specimen, con- 

 sisting of an encrustation of small white transparent crystals, the largest 

 being about ^ inch across. These crystals are all tabular, and consist of 

 the prism ooP (a), the macropinacoid ooPco (b), the brachypinacoid 

 ooPoo , and the basal pinacoid OP (d), thus forming octagonal plates. In 

 some crystals the macro- and brachypinacoids are developed to the extinc- 

 tion of the planes of the prism, when four-sides tabular plates are formed, 

 and in others again the macrodome ^ P oo (<?) and the brachydome Poo (/) 

 either bevel the edges of the macro- and brachypinacoid or completely ex- 

 tinguish them, giving rise to the following crystals : — 



3. Barytes ivith Quartz. — Opotiki. A massive variety of a yellowish 

 colour cementing irregular pieces of quartz. This specimen was presented 

 to the museum by the late Eev. Kichard Taylor. 



4. Radiating Barytes. — Waikouaiti. A specimen presented to the 

 museum by the Hon. W. B. D. Mantell, M.L.C. 



Witherite, Ba C. — The occurrence of this mineral in some of the mines 

 at the Thames is mentioned by Mr. Skey (Geol. Bep., 1870-71, p, 85), but 

 we have not, unfortunately, any specimen in the museum collection. 



Salts of Lime. 



Calcite, Ca C. — This mineral is so widely distributed in New Zealand in 

 various forms that it is unnecessary to refer to every instance of its occur- 

 rence which has been mentioned. 



Crystallized Calcite. — Dr. Hector mentions its occurrence in the tertiary 

 rocks of Otago (Jurors' Bep. N.Z. Ex., 1865, p. 3), as Dogtooth Spar in 

 limestone at Moeraki, and as Iceland Spar in limestone, marble, etc. 

 (Jurors' Bep. N.Z. Ex., 1865, p. 437); and Dr. v. Haast (Jurors' Bep. N.Z. 

 Ex., 1865, p. 256) mentions it in cavities of the volcanic rocks of Canter- 

 bury. Professor Liversidge also (Trans. N.Z. Inst., vol. x., p. 491) men- 

 tions 16 different specimens of calcite from Dunedin, which are all crystal- 

 lized as rhombohedrons or combinations of the rhombohedron and scaleno- 

 hedi'on. In the Colonial Museum we have the following specimens : — 



Calcite with Pyrites, Thames. — A massive crystalline variety with rhom- 

 bohedral cleavage and small rhombohedral crystals in cavity. Colour, 

 white. 



Calcite ivith Natrolite, Dunedin. — Small rhombohebral crystals B, and 

 also acute rhombohedrons in cavity in basaltic rock. Colour, pure white 

 and transparent, to dirty grey. 



