meteorite samples

For our first grinding trial, the small fragment from the rock meteorite was tested. The sample volume here is only 0.15 grams.

For the 20 ml grinding bowl used, we recommend adding at least 1 ml of sample volume to prevent damage to the bowl or grinding balls.

We ground the sample for one minute using the grinding balls made of hardmetal tungsten carbide with a maximum diameter of 10 mm. A fragment with a thickness of approx. 2-3 mm remained uncrushed in the grinding bowl. The impact energy of the small balls was too weak to grind such thick material. Thinner material was knocked off the original piece within this minute and ground to powder fineness (probably < 150-200 µm).

Provided that fillers (e.g. quartz sand) would not distort a subsequent analysis, the previously ground material could certainly be ground even finer after aggregation. In dry grinding, samples can be ground to d50 < 20 µm. Subsequently, further grinding in suspension would be necessary to achieve the finest possible results.

In the 80 ml grinding bowl made of hardmetal tungsten carbide, grinding balls up to 20 mm Ø can be used. Here, at least 10 ml of sample should be added.

For such small sample quantities, we would rather have recommended the use of a PULVERISETTE 0 Vibratory Micro Mill.

The second sample consisted mainly of iron. With a weight of only 0.05 g, the sample volume provided here was even smaller than in trial 1.

This sample was also comminuted for one minute as a test. Subsequently, the brightly polished grinding balls showed that very many ball-to-ball or ball-to-cup contacts took place.

The sample itself was also not significantly comminuted. The trial was stopped and the equipment was cleaned as best as possible with an appropriate portion of sand and water (grinding for 2 minutes).

The fragment of the iron meteorite was ground on our Vibratory Micro Mill PULVERISETTE 0 as a trial. Tungsten carbide can also be used here as an option.

The sample was mounted in a mortar on our Vibratory Micro Mill PULVERISETTE 0 and ground at relatively low amplitude (~1 mm) for 15 minutes.

After 15 minutes, only a few very small fragments were found in the mortar. It seems that the meteorite piece was plated by the bouncing grinding ball. Small fragments that detached from the specimen seem to have been re-laminated by the grinding ball onto other specimens.

Therefore, we do not expect the sample to be ground finer overall with longer grinding time. If necessary, the addition of a much larger amount of sand could also pulverize rolled-out material here. Also, cryogenic grinding could possibly grind magnetized material better.