gold source .......... auriferous quartz veins

The annual report published on thursday last week, had details about the selheim gold project that referred to the primary source of the gold mineralisation..... "appears to be auriferous quartz veins". (refer page 12 MXR 09 Annual Report)
"Further to Dr Russell’s work, Maximus has estimated from the total area of regional targets outlined, and the average gold content per square kilometre in known Inferred resources and Exploration Targets* that a separate additional Exploration Target* for the 12 other areas (Targets 4 to 15 in Table 2) totalling 5.9 square kilometres is from 9 to 12 million bcm of gold bearing alluvial gravels at a grade of between 0.3 and 0.5 g/bcm. As soon as the commercial plant is established and profitably operating, Maximus will commence outlining
this additional gold, which is expected to sustain longer term alluvial gold production from the Sellheim project".

If we take an average of the targeted gold in the 5.9 square km of .4 g/bcm from 10.5 million bcm, the target is 4.2 million grams of gold, which is 4,200 kilograms of gold at a current gross value in Australian dollars (at $36,921 per kilogram, last spot price per kg) of $155m. So I asked myself, where does this deposited gold come from?

In attempting to understand what gold from auriferous quartz veins is about, as far as identifying the obviously even higher gold content in the lode source, I found the following explanation which ends with reference to gold nuggets, which we know are at MXR's Selheim gold project.
From reading the extract below, I don't fully understand the article, but the last point (3) seems to be what we are looking at at Selheim. Whilst the gold in the sediments at Selheim is a large target, the biggest prize is discovering the lode source. The more I research the Selheim tenements and the surrounding gold mines, the more I like what I find.

" * Gold Placers: Placer deposits early provided man with the first samples of gold and since that time have accounted for a large production of the metal. If we include the Witwatersrand and other quartz-pebble conglomerates as fossil placers or modified fossil placers, then the placer type of deposit has provided more than two-thirds of man's store of gold. Before proceeding further certain terms with respect to placers should be defined. The term 'placer' is evidently of Spanish derivation and was used by the early Spanish miners in both North and South America as a name for gold deposits found in the sands and gravels of streams. Originally, it seems to have meant 'sand bank' or 'a place in a stream where gold was deposited'. While many other terms have been coined for deposits in weathered residuum and alluvium none is quite as succinct and expressive as 'placer'. The terminology of the zone or stratum containing an economic concentration of gold in eluvial and alluvial placers is varied. We shall use the miner's term 'pay streak', which is commonly used in Canada and the United States. Other English terms in use include 'pay gravel', 'pay sand', 'pay dirt', 'pay wash', 'pay channel', 'pay lead', 'run of gold', 'gutter' and 'wash dirt'. The tenor of pay streaks or of placer gold gravels and sands, in general, is referred to by the value (in ounces, grams, pennyweights, or in any unit of currency) per cubic yard or meter, per running length (foot or meter) of channel, per surface unite of cross-section, or per unit of surface (square foot or meter); also occasionally in bonanzas by dollars or some other unit of currency per pan. Note that placer deposits can be worked whose gold content is as low as 0.1 ppm. The pay streaks of placer deposits may rest on or near bedrock or on some stratum above bedrock. The bedrock in placer deposits is commonly referred to as the 'true bottom', although the term is little used today. When the streaks rest on a well-defined stratum of sand, gravel, or clay above the bedrock they are said to be on a 'false bottom'. Placers have been variously categorized, but here we shall use a simple nomenclature based upon whether the placers are formed by concentration of gold in situ over or in the immediate vicinity of primary deposits, namely 'residual' or 'eluvial placers', or by agencies that have concentrated the gold in the near vicinity or at some distance from the primary source. In the latter category we recognize 'alluvial', 'beach' and 'aeolian placers'. The terms 'saprolite' or 'saprolitic placer' were formerly used for certain types of eluvial placers, mainly in the eastern United States. Eluvial, alluvial, beach and aeolian placers may become buried after their formation and are sometimes referred to as 'buried placers'. These placers may be buried under: volcanic deposits as in California and Australia;
* glacial deposits as in Canada and Russia;
* talus and other slope deposits;
* aeolian deposits as in Australia;
* alluvial sands and gravels;
* marine and lacustrine deposits.

* The gold in auriferous placers may come from one or more of the following sources: Auriferous quartz veins and other types of gold-bearing deposits
* Auriferous sulphide impregnation zones, porphyry copper deposits.
* Auriferous polymetallic deposits.
* Slightly auriferous quartz stringers, blows and veins in schists, gneisses and various other rocks.
* Various slightly auriferous minerals such as pyrite and other sulphides in graphitic schists and other rocks.
* Slightly auriferous conglomerates, quartzites and other rocks.
* Old placers (palaeo-placers).

* It should be noted that the geological history of productive placers is frequently complex, much more so than the sequence: primary vein or lode source.
* eluvial gold placer.
* alluvial gold placer. Often an intermediate collector of gold is involved, mainly auriferous conglomerates, quartzites, etc. A number of variants are recognized in the lode-placer sequence as follows:

1. (a) lode - deluvial placer - interceptor - alluvial placer, (b) lode - interceptor - alluvial placer, (c) interceptor - alluvial placer. The primary agent that produces the various types of gold placer is weathering; a process that involves numerous complex chemical reactions. Three things may happen to gold in primary deposits: The gangue minerals may be disintegrated and leached away, leaving the gold relatively untouched; the gold may remain in situ in the oxidized zones or pass into eluvial and alluvial placers;
2. The gold may be dissolved and carried far away from the deposits in which case no placers are formed; or
3. The dissolved gold may be wholly or partly reprecipitated on nuclei of gold in the residuum or on similar nuclei as they are moved along in the alluvium of streams, rivers, beaches, etc. The last process is largely responsible for nuggets".

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