880 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 4 inch across. These crystals are all tabular, and consist of 
the prism oP (a), the macropinacoid œPæ (b), the brachypinacoid 
œP , and the basal pinacoid OP (d), thus forming octagonal plates. In 
some crystals the macro- and brachypinacoids are developed to the extine- 
tion of the planes of the prism, when four-sides tabular plates are formed, 
and in others again the macrodome 4 Pao (e) and the brachydome Po (f) 
either bevel the edges of the macro- oni brachypinacoid or completely ex- 
tinguish them, giving rise to the following crystals :— 
ea 
Sy sm om ge 
9. Barytes with Quartz.—Opotiki. A massive variety of a yellowish 
colour cementing irregular pieces of quartz. This specimen was presented 
to the museum by the late Rev. Richard 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. Rep., 1870-71, p, 85), but 
we have not, unfortunately, any specimen in the museum collection. 
BALTS or Lime. 
Calcite, Ca C.—This mineral is so widely distributed in New Zealand i 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’ Rep. N.Z. Ex., 1865, p. 8), as Dogtooth Spar in 
limestone at Moeraki, and as Iceland Spar in limestone, marble, ete. 
(Jurors’ Rep. N.Z. Ex., 1865, p. 487); and Dr. v. Haast (Jurors’ Rep. N.Z. 
Ex., 1865, p. 256) mentions it in cavities of the voleanic 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- 
hedron. In the Colonial Museum we have the following specimens :— 
Calcite with Pyrites, Thames.—A massive crystalline variety with rhom- 
bohedral cleavage and small rhombohedral orystels in cavity. Colour, 
white. 
Calcite with Natrolite, Dunedin.—Small rhombohebral cista. R, and 
also acute rhombohedrons in cavity in basaltie roek. Colour, pure white 
and transparent, to dirty grey. 
