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342                        MINERAL RESOURCES, 1914----PART I.
a platinum determination. Among the material that floated was graphite, sericite, mica, and gold. As I did not find any other platinum-bearing ore in the graywacke, I am forced to assume that the precious metals are associated with these specks, particularly as they are found especially in the cement. What is more striking is that these specks are sometimes found in the quartz. * * *
Of particular value to the investigation of the origin of the graywacke frag­ments is the segregation of certain constituents. Pufahl has treated 200 grams of finely ground pulp for weeks with hydrofluoric acid and concentrated sul­phuric acid. After the first attempt, there was still quartz in the residue, while after a second trial the residue was free from quartz. The insoluble consisted of 0.044 gram of heavy precious metal residue and disintegrated chrome iron ore. With this precious metal residue there was considerable zircon, with its characteristic radioactive rays. In one residue a small amount of platinum was determined which figured on 1 ton of residue would amount to 1.15 grams. The extraction was made in a platinum crucible and it is not impossible that it may have been derived from that source. * * *
Pufahl determined the presence of the following metals in the ore: Cr, Pt, Ir, Fe, Au. Hommel determined Cr, Ni, As, Sb, Fe, Cu, Pb, Zn, Ag, Au. In this aggregate it is well to separate the earlier ones from those that came later. The later ones would be Cu, Pb, Zn, As, Sb, Ag. The original ones are probably Cr, Ni, Fe, Pt, Ir, Ag, Au. The later minerals are probably derived from basic eruptives. Until now it has been impossible to get any idea as to the origin of the platinum or its chemical combinations. * * *
The principal production of platinum is in the Urals and a little from British Columbia, in which regions the deposits result from the destruction or dis­turbance of primary deposits re-formed through the agency of water. While the mineral is not in commercial quantity in the primary deposit, the distribu­tion of the mineral in the secondary deposits has permitted commercial extrac­tion. A comparison of these well-known deposits with the newly discovered ones in the Rhine slates shows that the platinum in these latter show the same chemical association as the primary deposits in the Urals and British Columbia. One is practically forced to the conclusion that in the Rhine slates the origin is connected with a basic eruptive, probably peridotite. To differentiate the platinum-bearing graywacke from the Ural and Canada formations, it can be said that they have a great geologic age and were consolidated by a cement.
The granite pebbles in the conglomerate point to the existence of the granite in depth. They belong to the basal formation which is overlain by the gray­wacke to an unknown extent. This basal complex could also contain the platinum-bearing basic eruptives and the primary gold. The sea during Silurian and Devonian times disturbed this basal complex and transported the precious metals into certain definite strata. Later these platinum-bearing beds were again partly disintegrated and the fragments cemented in younger, higher horizons. This explains the wide distribution of the precious metals through so many horizons. They are the product of continual destruction of older beds and the building of new sediments. * * *
As this is a matter of precious metals, I will depend only on my own sampling and tests. I used the greatest care, taking 2-kilogram samples, which were lead sealed in boxes on the spot. In addition to these, I took larger samples weighing from 20 to 40 kilograms and put [them] in the usual sacks. As I could not give these sacks the attention I desired, I only lay stress on them in so far as they agree with the sealed samples. In testing this material it is necessary to use a fine mesh, namely, 280 to the inch. From my experience it is desirable to use the largest possible quantity of pulp. In the dry work never less than 200 grams, and preferably 300 grams, should be fused. In the wet methods 1 kilogram should be used. If platinum tests are made in different laboratories, or if the same test for platinum is made in the same laboratory several times, surprisingly divergent results will be obtained. For example:
First test:                                                                               Grams per ton.
Laboratory A_____________________________________ 30
Laboratory B_____________________________________Trace.
Second test:
Laboratory C-------------------------------------------------------- 33.5
Laboratory D---------------------------------------------------- 3.8
Third test:
Laboratory E______„______________________________ 8.0
Laboratory F-------------------------------------------------------- .8