The complete instructions are available as a pdf document: click here
The following instructions apply to silicate and carbonate rocks. Production of pills from non-silicate (or carbonate) rocks without prior approval and instruction of the laboratory leader results not only in significantly more work (preparation, measurement, interpretation) but also results into errors of the instruments and of the final results. No observance can result into exclusion from laboratory work and possible compensation payments. This is especially the case for rocks with an ore content >5% (esp. sulphidic), sulphates, slag and flint.
Sample selection
The sample/specimen should be fist-sized, about 200-500 g, and shouldn’t have any veins, paint (sample numbers etc.), grease from the saw, or weathered sections.
We advise to group samples of similar composition and to treat them group wise. This reduces the probability of contamination! Setting up a sample list with priority assignment is strongly recommended:
Sample list (with priorities!):
- own name, exact sampling location, date, unit, etc; representative for what? use/scientific question?
- field description (rock type), macroscopic classification
- microscopic description (texture, mineral content, rock type)
- amphibole content, ore content (sulphide, oxide), approx. content of hydrous minerals
- sample ID (alphanumeric, no symbols, max. 7 digits) and relative priority
Jaw crusher & hydraulic press
Jaw crusher : use for large samples, only. Crush the clean sample and use a hand magnet to remove metal splinters or fragments (contamination!). We advise to run a sample first at a wide setting, and then an additional time at a finer setting. Attempting to crush a large block at a fine setting frequently results into the rock being stuck between the jaws.
Hydraulic press : use for normal to small sized samples. Place isometric cuted pieces or grains of maximum diameter of 20 mm on the anvil. Crush them to 1-2 mm-sized grains. Do not overpress the rocks (the machine sound changes and the motor switches off after a while). Rather remove the vessel, rearrange the pieces, crush again. It usually takes ca. 5 times per sample.
Both devices should be cleaned using the air hose and acetone. Do not use water! Rust leads to elevated Fe, Ni & Cr values!
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