Instructions for Users:

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We have a range of mills available for different applications. They subdivide into:

• agate & ceramic mills
• thungsten carbide mills
• steel mills
  

  
  

  			Two large volume agate mills (reserved for ultramafic rocks), one small agate ball mill, and one ceramic shatterbox/agate ball mill. There is also a range of very-small-volume ball mills (steel and agate) available for radiogenic isotope preparations (not shown). These mills are used for trace- and ultratrace analytical preparations. Grinding is only allowed on setting 1 of the excenter rotor.
  	Two general purpose WC (thungsten carbide) mills are used for all "normal" rock grinding applications of silicate and carbonate rocks. WC is the hardest of all mill materials, but much more brittle than steel. The small volume mill has a base plate adaptor (shown in the center).					Three steel mills for different sample volumes. The smallest one uses the same adaptor as the small WC mill. They are used to grind very hard rocks, such as eclogites. Steel flakes coming off are removed using a hand magnet. The Cr, Ni and Fe values are thus to be interpreted with caution.

  
  

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  Below you see how our two identical excenter rotor bases look like that rotate the mills on two possible settings. At the bottom, the mill is held in place by a fixed steel ring and a rubber liner.
  
  It has proven useful to use two sheets of paper between the rubber and the steel of the mill body. This is in order to prevent rubber sticking to the mill that can later fall into the sample when it is removed from the mill after grinding. The top is fixed by a dual steel clamp.
  
  

  				fixing the steel clamps
  	Loading the mill

For information about contamination associated with the different disk materials, see here.

Instructions:

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Powder sized sample grains of equal size but different density will vertically separate if you only tap the jar on the table too hard. Inhomogeneities and unknowingly wrong or not at all interpretable results follow.

fair split

Fair-split and reunite the crushed sample several times: on white printing or wax paper, separate a symmetric pile of the powder into four sections, using a spatula. Re-unite facing quarters in diagonal direction.

piece out method

Piece out a fraction of the sample from a sample cone using a tube end (1.5 – 3 cm diameter, bring your own; alternative to fair split). See splitting devices on picture below.

shaking

Shake the sample well, in a plastic bag or pot, together with two agate balls, by rotation & eccentric shaking over a horizontal axis (homogenizing!).

Before You Leave:

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