Scanning Electron Microscopy (SEM) with AMICS Analysis Tools

MLA and AMICS analysis are Scanning Electron Microscopic (SEM) based analysis which determines minerals based on backscatter and Energy Dispersive X-Ray (EDX) analysis. For scatter images, grey scale is used and the brightness is based on the Z (average atomic value) number.

For example, quartz particles are considered grey while galena gold particles are usually white compared to the grey scale. Sulfide containing minerals, such as pyrite, are brighter than the silicate minerals. From the grey scale backscatter observation, x-rays (EDX) are take and compared to a known file or generated from the sample itself. Minerals or phases can be identified.

AMICS Backscatter Image

From backscatter images, grey levels are used to help determine mineralogy. For every grey level, sometimes multiple levels within one particle, energy dispersive x-rays ( EDX) are collected.

From grey levels, black is the carbon coating background, darker grey particles are usually silicates, and brighter particles are sulfides. From this image, no gold or galena is observed since the particles would be bright white.

AMICS False Color Image

From backscatter images and grey levels, x-ray are taken based on the different grey levels within the particles. For example, some particles only require one x-ray while multiple particles require multiple x-rays.

For the false color image, the colors merely reflect on how many x-rays were taken for each particle. They are not identified until the next step of verification with a known mineral library standard. The minerals itself are used to determine the library.

AMICS Identified Image

After collecting standards and processing, minerals are identified and colors can be replaced to determine overall mineralogy. In this sample, yellow indicates quartz, light green indicates clinochlore, red is pyrite, and dark green is chalcopyrite. The technology is robust enough to let the user pick mineral of interest and can easily change the color to their preference.

AMICS Copper Particles

From AMICS data, particles can be lined up to determine mineral liberation along with mineral association.

In this case, the green (chalcopyrite) particles are very liberated at this size range with minor pyrite (red), chlinoclore (light green), and quartz (yellow) association.