JOURNAL OF THE CHEMICAL SOCIETY 1.-On Narnaqualite. By Professor CHURCH,M.A. (Read November 18th 1869.) Mr. J. R. GREGORY lately brought from Namaqualand South Africa some small specimens of an apparently new copper mineral. He directed my attention to the substance as worthy of investigation. My results are here given in a condensed form. Namaqualite occurs in thin layers of silky fibres which are true crystals though their minute size and the general absence of distinct terminations renders it impossible to ascertain the system to which they belong. The layers alternate with irre- gular bands of a kind of chrysocolla and are sparingly mixed with small crystals of magnesia mica. The aspect of nama- qualite resembles that of chrysolite but its colour is pale blue with a silky lustre.Its hardness is 2.5 and its density 2.49. Isolated crystals appear transparent under the microscope. In the closed tube it gives off much waterwhen heated becoming black. For analysis the mineral was coarsely crushed and the homogeneous fragments carefully picked out under the micro- scope. The powdered selected pieces lost nothing in weight either over sulphuric acid in vacuo or at looo. The several samples however were always submitted to the temperature of 100' before analysis. The following results were obtained with different speciniens. Unfortunately the quantities em-VOL. XXIII. B CHURCH ON NAMAQUALITE. yloyed were small on account of the present rarity of the mineral.I ought to state that the alumina found contained some ferric oxide; how much I could not successfully de- termine. ANALYSES OF NAMAQUALITE. Analysis. Substance HzO. CuO. A120+ CaO. P2MgzOp SiOz. taken. I. '098 0.315 --L -11. *113 -037 -017 -00095 -111. -257 0082 -116 --IV. -174 0055 *0772 -027 *0035 *0165 -7- v. *111 --*0025 The foregoing results translated into percentages are as follow :-I. 11. 111. IV. V. H20 .......... 32.14 32.74 31.91 32-75 - CUO .......... -45.09 44.38 - AlQO,..8 . .. . -15-04 -15.52 -7 CaO .......... -2-01 - MgO .......... -3-01 -3.42 I Si0 .......... --2.25 The mean percentages deduced fro^ these numbers are :-H20 ............... 32-38 cuo ................ 44.74 A120 ................15-29 CaO ................ 2.01 MgO ................ 3.42 SiO ................ 2-25 100*09 if we exclude the silica as an intruding substance while we regard the limp and magnesia as replacing a small part of the cupric oxide in this mineral we may I think reasonably regard it as a compound of 4 molecules of cupric hydrate 1 molecule of aluminium hydrate and 11 molecules of water. The oxygeu- ratio between the protoxides the aGminium oxide and the water is 4 :3 :11 nearly and corresponds to such a view. CHURCH ON NEW AND RARE CORNISR MINERALS. 3 The suggested formula demands the following percentages (for comparison I have placed the mean experimental results in juxta-position) :-Theory 4CuH202. Experiment.A12H606..-.4 aq. 4CuO ...... 79.5 x 4 = 318....:. 51.37 44.74 A1,0,. ..... 103 = 103.. .... 16-64 15.29 11H20 .... 18 x 11 = 198.. .... 31-99 32.38 100*00 This mineral belongs to the rare class of hydrous oxides in which a protoxide and sesquioxide are united. Hydrotalcite (A1,H6O6.6MgH2O,. 6aq.) and pyroaurite( Fe2H606. 6MgH20,.6aq.) seem to be its nearest allies. The fact that it is crystallised as well as definite and constant in composition demands for it specific rank. I am indebted to Mr. J. R. Gregory not only for the several specimens of namaqualite which I have examined but also for pointing out the novelty and interest which would probably belong to a careful analysis of the mineral. My thanks are due to my assistant Mr. E. Kinch for the care a,nd skill with which he has executed much of the fore- going analytical work.