The annotated modified image above shows white magnetiteFe oxide, FeFe2O4, containing oxidized iron (Fe) found in the matrix of carbonaceous chondrites and as diagnostic component in CK chondrites. In CK chondrites, magnetite is typically chromian, containing several wt. % Cr2O3. Click on Term to Read More (avg. Z~21); light gray olivineGroup of silicate minerals, (Mg,Fe)2SiO4, with the compositional endpoints of forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Olivine is commonly found in all chondrites within both the matrix and chondrules, achondrites including most primitive achondrites and some evolved achondrites, in pallasites as large yellow-green crystals (brown when terrestrialized), in the silicate portion Click on Term to Read More (avg. Z~15), gray glass (avg. Z~13), and black plagioclaseAlso referred to as the plagioclase feldspar series. Plagioclase is a common rock-forming series of feldspar minerals containing a continuous solid solution of calcium and sodium: (Na1-x,Cax)(Alx+1,Si1-x)Si2O8 where x = 0 to 1. The Ca-rich end-member is called anorthite (pure anorthite has formula: CaAl2Si2O8) and the Na-rich end-member is albite Click on Term to Read More (avg. Z~11). Image credit: geoinfo.nmt.edu
High energy primary electron that suffers large angle (> 90°) scattering and re-emerges from the entry surface of a specimen. Backscattered electrons usually have energies close to that of the primary electron beam. They are valuable in microanalysis because their number depends on the average atomic numberA number equivalent to the number of protons in the nucleus of an atom, commonly abbreviated as Z. Click on Term to Read More of the sample.
Compositional variations (variations in average Z) can be imaged by mapping backscattered electron intensities.
Some or all content above used with permission from J. H. Wittke.
