102 

 APPENDIX. 



BEPOET ON THE DTSCOYEET OE DIAMONDS AT BAID HILL, NEAB 



HILL END. 



UniTersity of Sydney, 



December 5, 1873. 



To the Hon. the Minister for Lands. 

 Sir, 



In reply to your request of the 2nd instant, I hare the honor to 

 furnish you with the folloTVT.ng particulars relating to the mineral specimens 

 from Bald Hill, near Hill End, which accompanied your communication. 



Diamonds — Three in number ; the largest of them is in the form of a six- 

 faced octahedron, rather flattened, owing to four of the groups of faces being 

 more highly developed than the remaining four. The faces and edges are 

 rounded somewhat, but this has not been caused by attrition ; diamonds often 

 appear as if water-worn, but in reahty this is seldom the case ; the rolled and 

 water-worn appearance is due to the fact that the diamond usually crystalhzes 

 with curved faces and rounded edges. It is clear and colom-less, and perfectly 

 free from all visible internal flaws ; the surface is likewise free from flaws ; 

 but scattered over some of the faces are a few minute and insignificant 

 triangular markings, but these are quite superficial and will disappear during 

 the ordiuai-y process of cutting. It possesses a specific gravity of 3 '58, and 

 weighs 9"6 grains (Troy), i.e., a little over thi'ee carats. It is generally 

 calculated that diamonds lose one-half their weight during the process of 

 cutting and polishing ; and their true value cannot be ascertained until this 

 has been done. Tlie diamond next in size possesses the same ci'ystallographic 

 form as the one above mentioned, but is not so much compressed. It has a 

 weight of 4"5 grains (Troy), or nearly one and a half carats. It has a chip 

 on one edge, and contains a speck of foreign matter. It is a straw-colour. 

 The smallest diamond weighs about half a grain ; it has the form of a six- 

 faced tetrahedron, and possesses a high lustre, but is rather off colour. 



Accompanying the diamonds were two small specimens of gem sand. 



Gem Sand No. 1. 



In this the following substances were found to be present : — 



I. Corundnm — When blue this is known as the sapphire, and when red as 

 the ruhi/. 



(a) Common Corundum — Present in small fragments of bluish, greenish, 



and grey tints. 

 (&) Sappliire — In small particles of a blue colour, some so dark as to 

 appear almost black, and others very light. Some of the fragments 

 still show their crystalline form, viz., a hexagonal pyramid, but most 

 of them do not, and are either much rolled, subangular, or angular 

 in their outline. 

 The ruby is absent, but probably would have been present had the sample 

 of gem sand been larger. 



II. Zircon — Plentiful, usually in the form of much rolled pieces. Generally 

 of a brown colour, sometimes red, and at others nearly colourless. The small 

 and nearly colourless crystals possess a very high lustre, almost equal to that 

 of the diamond, so that they might readily, without careful examination, be 

 mistaken for that gem. 



