80 On the Ornamental Stones of the Colony. 



irregular pieces is found in veins in the decomposed older 

 basaltic rocks of Phillip Island, and can be collected in great 

 abundance along the sea-beach at the foot of the basalt 

 escarpment. Most of the pieces have a neat pattern formed 

 by alternating concentric white and bluish- white bands ; 

 several centres often occurring on one stone. Many have 

 fissures or cracks in them ; the sides of which are often 

 coated with quartz crystals • in others, these fissures are 

 filled with carbonate of lime. Remembering the successful 

 practice carried on for many years by the lapidaries of 

 Oberstein and Idar, in Germany, of artificially colouring 

 common chalcedony, producing, by chemical means, bands 

 and spots of different colour throughout the stone ; making 

 them thus look like chrysoprose, agate, onyx, sardonyx, &c, 

 a few preliminary experiments have been made in the 

 laboratory with pieces of chalcedony from Phillip Island, 

 with a view to producing artificial onyx 5 and the results 

 have been so far successful as to permit the hope that if the 

 process was properly executed according to the now known 

 process, good artificial onyx's could be produced. 



This art of colouring stones was according to Pliny known 

 to the Romans. He says in the 7oth chapter of the 37th 

 book, that certain geramse of agate (cochlides) might not 

 be natural, but artificially made. He further narrates that 

 glebse (nodules of agate) were found in Arabia ; which, if 

 boiled in honey for seven days and nights for the purpose of 

 cleansing them from impure and earthy matters, could then 

 be prepared by artists in such a manner that they received 

 coloured bands and spots. 



This secret seems to have been lost for a long time ; but 

 during the last century the Roman lapidaries were known 

 to possess it. They collected the chalcedony from the 

 German miners, sending travellers for the purchase, who, by 

 some secret process detected the stones fitted for the purpose. 



This manner of trading attracted attention, and the secret 

 was bought from an Italian traveller by a miner who first 

 secretly practised it by himself, but it since became generally 

 known, and is indeed very simple. Specimens of chalcedony 

 which contain amongst the concentric or parallel veins some 

 that are softer, and therefore, more permeable by fluids, are 

 chosen ; and this property can be tolerably well detected by 

 mounting the stone and noticing whether any absorption 

 takes place. The stones which shew the greatest irregu- 

 larity in this respect are the best fitted for the purpose. The 



