The Bureau of Algerian Mining Research is at the present time conducting surveys in the region of Hoggar, in the Tamanrasset area, not far from the Niger frontier, for the possible presence of diamonds and platinum.
Pan of landscape
Various of men digging
SV. Men sifting.
CU. Man sifting.
Various of men sifting
Men checking contents on ground
Wide of operation
Men planting explosives into ground
Man detonating explosion
Explosion in ground
Men putting rocks into machine
More of men sifting
SV. Man sifting in water.
LV. Man sifting in water.
LV. Man working in lab.
SV. Liquid coming out of machine.
SV. Machine pan down to liquid on tray.
CU. Liquid being vibrated.
CU. Vibrating liquid.
SV. Two (2) men sifting bath of liquid.
LV. Separation Room pan to machine.
SV. Man working at machine.
LV. Men at bench pouring.out liquid.
CU. Liquid into glass.
LV. Man pouring out Liquid.
CU. Liquid into container.
SV. Man at bench holding precious metal over burner.
SV. Man with instrument.
SV. Man with tweezers holding precious metal.
CU. Sign "SPECTHOGRAPHIE".
GV. Man working at table.
SV. Box - instrument working.
SV. Meter board.
CU. Meter registering.
SV. Man with instrument.
SV. Light in Cabinet.
CU. Man watching.
SV. Man seated at table with instrument.
CU. Man seated at table with instrument.
Background: The Bureau of Algerian Mining Research is at the present time conducting surveys in the region of Hoggar, in the Tamanrasset area, not far from the Niger frontier, for the possible presence of diamonds and platinum.
As for diamonds, there are encouraging indications in dried up river beds and wadis. Indeed, at Silet a mountain of boulders and rocks had a content of 10 to 20 grammes per ton, an average of about 15 grammes a ton. The mineral veins in other parts of the world are known not to exceed 11 grammes per ton.
For diamond research, trenches are dug in the river beds down to the granite base. The alluvium thus excavated undergoes a first separation in a vibrating sieve to eliminate minerals of weak density. Selected alluvium is transported by waggon to a washing station situated a few kilometres away where the sands are subjected to a special examination by action of gravity. When this is carried through the mas of sand is removed from the mould and a black circle is ringed in the centre, then put into bags for transport to the laboratory at Algiers.
Near Silet a mountain of serpentine stone many kilometres long....the mountain at Tibeghin, contains without doubt the richest stratum of platinum in the world. The samples obtained undergo a treatment similar to that of the diamons.
In the modern laboratories in Algiers samples of stone and soil from Hoggar are scientifically analysed. The concentrated alluvium is finely crushed in a pebble crusher. This method prevents the spoiling of any diamonds that may be present. After crushing a new concentration is obtained with the aid of "vibrating tables". The concentration emerges from the table, and finally a concentration by magnetic separation.
In this operation the soil flows over an endless belt and over a very powerful magnet which attracts away the grains of iron oxide and nickel. After separation the samples are returned for tests on the reaction of methylated iodine. If diamonds are found in the samples, these fall to the bottom and other bodies remain on the surface. The final operation ...the diamonds are loosed from their matrix are by heating in an alkali liquor.
The analysis of the platinum is identical to the diamonds except for the final operation which is omitted. The nuggets of platinum are weighed. But a new method is employed to reveal the platinum. Known as the spectograph method, the concentrated alluvium is mixed with powdered graphite to render it a good conductor of electricity and then placed in a carbon arc. The light produced by the arc is split up by a prism and recorded on a sensitive plate. After development this plate presents a series of very fine lines representing the spectrum of the different metals contained in the samples. Nothing now remains but to examine the plate for density before tracing the curve of the gamma image and sound. This method has the advantage that it indicates the amount present not only of platinum but of other metals as well.