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Element maps are often displayed in false color, which helps the human eye distinguish subtle variations by expanding the range of visible hues. In these examples, the chemical zonation in plagioclase is clear for the elements Na (left) and Ca (right). Unlike back-scattered electron images ( BSE), which only show average Z in a phase, element maps show the true spatial distribution of each element of interest.

Because the dwell times are typically shorter than in WDS analysis, elements in low concentration may not give a response.Įlement maps showing Ca and Na zonation in plagioclase.

Element maps are recorded digitally and can be saved to use as sample maps for locating spot analyses.

Element maps give a complete 2D picture of internal chemical zonation within a mineral, which is more informative than a simple line traverse.

Maps of different elements over the same area can help to determine what phases are present.

Element maps show the spatial distribution of elements in a sample.

The best element maps are acquired using a WDS system on an electron microprobe, but the trade-off in using the spectrometers is longer acquisition time. This is typically a faster approach, but sacrifices resolution and detection limits. In many cases, adequate element maps can be acquired by EDS systems. Greater distinction can be made by longer analysis, but at the cost of time. Resolution is determined by beam size, and relative response of each element is determined by how long the beam dwells on each point (and of course the actual concentration). Think of an element map as a pixel by pixel (bitmap) image based on chemical elements. Either way, the image is produced by progressively rastering the electron beam point by point over an area of interest. One can use either an EDS or WDS system to produce an element map. Element maps are extremely useful for displaying element distributions in textural context, particularly for showing compositional zonation. Because it is acquired from a polished section, it is a 2D section through the unknown sample. DetailsĪn element map is an image showing the spatial distribution of elements in a sample.