Which phase(s) contain the element I care about?

Which phase(s) contain the element I care about?

If you just want to know which mineral phases contain a specific element the three-colour + elevation images are the way to go.  The below sample contains a variety of sulphide minerals which are easily distinguished based on their relative concentrations of sulphur, iron, and copper by setting each of three colour (red, green, & blue) to each of these elements.  One can then set elevation to the element of interest (in this case mercury) and rotate the image to see which phases contain that element.

Trace Element Maps: Sulphide minerals

These images were produced for a Master’s thesis ("Metal deportment of Maurliden", Dominique Brising, Freiberg 2016) on samples from the Maurliden Mine in northern Sweden. The composition image maps are produced by LA-ICP-MS, and show the composition of sulfide minerals (sphalerite & pyrite) from the mine area. They are overlain on a reflected light photograph of the sample itself. The analysis square measures 180 x 160 µm, and was produced by a series of laser line scans 5 µm wide.

Sample

The colour scale has been adjusted for each element so that only the areas with higher concentrations are visible, so that the underlying photograph can be seen in areas of low concentration, which makes it is easy to tell which minerals contain which elements.

Many thanks to Boliden Minerals, AB for permission to use these images on this web page.

Trace Element Map: Garnet

The left hand image shows a thinsection of an ore-assiociated garnet-bearing schist from northern Sweden, while the right hand photo shows a trace-element composition map, which has been overlaid upon a copy of that image.

The map was produced by a series of laser line scans, each of which is 50 µm wide.  The entire image is ~5 mm wide, which means that a full experiment on this scale takes about six hours to run, including analysis of a standard reference material before and after the line scans.

2016

The feature of interest here is the large garnet grain at the center of the image, which, like many garnets world-wide, shows noticeable zoning in its composition, especially with respect to yttrium (Y).

Many thanks to Boliden Minerals, AB for permission to use these images on this web page.

Thinsection of an ore-assiociated garnet-bearing schist

The below images show two views of a thinsection of a garnet-bearing schist from northern Sweden, and their corresponding trace-element composition maps, which has been overlaid upon a copy of sample photo.

Sample garnet map

The map in the upper pair of images was produced by a series of laser line scans, each of which is 50 µm wide.  The entire map is ~5 mm wide, which means that a full experiment on this scale takes about six hours to run, including analysis of a standard reference material before and after the line scans.

The map in the lower pair of images was produced by a series of laser line scans, each of which is 35 µm wide The entire map is ~3 mm wide, which means that this experiment took about four hours to run.

The feature of interest here is the large garnet grain at the center of the image, which, like many garnets world-wide, shows noticeable zoning in its composition, especially with respect to yttrium (Y).