80 GEMS OF AUSTRALIA. 



Mineralogists have classified those substances into Six Systems, 

 the names of which vary with each writer. The accompanying 

 chart is prepared by the present Author from the most approved 

 text-books, in order to elucidate by a tabular arrangement those 

 several systems. 



It will be seen that only two or three crystals of each system, 

 including the "primitive" octahedron or dodecahedron, as the case 

 may be, are delineated ; but infinite modifications and combina- 

 tions of the simple forms occur in each system, presenting the 

 most complex and beautiful forms of crystallization. 



Professor Mohs, in his valuable work on Mineralogy, has 

 figured no less than 277 crystals belonging to the several systems ; 

 and many more might be added. 



It is worthy of remark, as bearing upon Australian Gems, 

 that the author of this paper has for upwards of twenty years 

 been in the habit of studying the mineral productions of Australia, 

 using the assay-balance and all other tests, except chemical, in 

 case of any doubt or difiiculty ; and his experience justifies him 

 in asserting, that he has invariably found Nature so true to herself, 

 here in Australia, as in other parts of the "World, that he has 

 frequently brought out the specific gravity of any mineral — the 

 gems especially — to a decimal of a thousandth, when referring to 

 that specific gravity as given by themostesteemed writers.* Hence, 

 when weight, hardness, crj^stalline form, and colour, coincide with 

 those " laid down in the books," he has always felt safe,iu pronounc- 

 ing confidently upon the mineral substance under investigation. 



The small Cabinet of Gfems now submitted to the Members of 

 the Eoyal Society affords a fair sample of the quality, if not of 

 the size of Australian Gems, — found, as they are, through the 

 length and breadth of this great island continent, under precisely 

 the same conditions, and accompanied by the same minerals, as 

 when found in situ in other localities in the several gem-producing 

 Countries. They include in their catalogue almost every precious 

 stone known to mankind, including the Noble Opal, — splendid 

 specimens of which, of great fire and brilliant colours, have lately 

 been brought to Sydney from the far North-west, and which will 

 bear comparison with the finest specimens from the famous Opal- 

 mine of Czerwenitza in Hungary. And when it is borne in mind, 

 that during this month an Octahedral Diamond, exceeding 12 carats 

 in weight, has been brought to Sydney from the banks of the 

 Macquarie Eiver, — that sapphires of great size and beauty, — red, 

 yellow, blue, and green, — a pearl weighing 83 grains, — large 

 topazes of all colours, — hyacinths of great fire and clearness, — 

 besides other gems (including forty-one diamonds from a new 

 locality), — are now placed before the Eoyal Society, we have 

 a right to predict that the day is at hand when the Gems of 

 Australia will be sought for as articles of commerce. 



* See instances mentioned ante, p. 78. 



