174 THK VICTOUIAN NATUUALIST. 



members, who secured specimens of the wood ; this by the way, 

 shows no greater alteration than a piece of Irish bog-oak, 

 although it has been in actual contact with the lava. On a 

 former visit the writer found a gnarled stump enclosing a piece 

 of basalt within a hollow on the side of the stem. 



The few hammers available were then speedily brought into 

 use, and the quarry resounded from the energetic blows of the 

 members searching for minerals. They were rewarded by finding 

 some interesting and often choice specimens of mammillated, 

 radial, and stalactitic Aragonite and Ferrocalcite, wliich in their 

 setting of blue Vivianite in the vesicles presented an extremely 

 pretty appearance. The structure of the basalt from the two 

 principal flows seen in the quarry was explained for the members 

 by means of sections under the microscope provided for the 

 purpose. 



On the party emerging from the quarry by an easier path at 

 the south end, a stack of short but very perfect columns was 

 examined, which form a causeway between two water-filled quarry- 

 holes. The ball and socket joints of these columns forcibly 

 reminded some of the members who had visited Ireland of 

 those at the Giant's Causeway. 



The minerals seen in this quarry during the afternoon were 

 the following : — Calcite, Aragonite, Ferrocalcite, Magnesite, 

 Vivianite, Limonite, Copperas, and Marcasite. The occurrence 

 of Vivianite, which is almost exclusively confined to the vesicular 

 layer at the bottom of the basalt flow, may be the result of the 

 liberation of phosphoric acid or phosphate of ammonia from the 

 decomposing animal matter usually met with in similar silty and 

 peaty deposits, such as would have existed here. 



Although this seems to be the first visit of the Club to the 

 Burnley quarry, its many points of interest, both scenic and 

 scientific, together with its accessibility to town, should make it 

 a more frequent resort for those interested in the study of 

 geology. 



Note on the Microscopic Structure of the Basalt in 

 Messrs. Willis's Quarry. 



Sample i. — A compact bluestone, which rings under the 

 hammer ; from the lower part of the quarry. This is a fresh 

 Olivine Basalt, with holocrystalline and pilotaxitic structure 

 (completely crystalline and with fluidal structure in the ground- 

 mass). The base consists of a closely felted mass of slender 

 plagioclase crystals with a general parallel arrangement. The 

 felspar laths are often strongly bent. The interstices between 

 the groups of felspar laths are filled in with granular purplish 

 Augite crystals ; sometimes these crystals, however, are idio- 

 morphic. Magnetite is freely scattered throughout, the crystals 

 often showing parallel grouping, sometimes arranged in the line 



