This is Frank's first instructional video, and he has chosen to go through an example of the normalization of microprobe data for an epidote-group mineral (which is a relatively straightforward example, but also one that has a few complications that makes it of particular educational value). And the hints and suggestions here should be broadly applicable to most mineral normalizations. Again, his first video, so yes, there are some technical issues. There are a couple of very brief sound glitches in this (and yes, he lives near a fire station), and by around the 2-minute mark you'll probably be tired of how often I say "ah" and "actually" (enough times to "actually" make a fun drinking game), but if you can ignore those beginner pitfalls, Frank thinks you'll end up with a pretty good and really detailed idea of how a general mineral normalization is put together, and from this specific example you'll also learn quite a bit about epidote-group crystal chemistry.
Note: if you'd like to work through a more introductory video series on mineral normalization, check out this playlist covering the derivation of amphibole formulas from microprobe data: https://www.youtube.com/playlist?list... Feel free to add comments or questions below, and check out my website at www.rockptx.com for more educational material, tons of scanned images of cool thin sections (including the rock this analysis comes from), analytical data, and lots of additional information. Video time index: 0:00:08 Introduction & looking at the raw weight percents. 0:06:19 Converting raw weight percents to raw moles. 0:14:24 Calculating the normalization factor. 0:19:50 Calculating the charge balance: part 1. 0:29:04 Deriving the equation to estimate (Fe+Mn)3+. 0:36:41 Calculating the charge balance: part 2. 0:48:49 Calculating normalized moles & assigning them to sites. 1:07:55 Deriving the mineral name. 1:18:23 Calculating oxide weights. 1:32:12 Estimating the non-measured HREE content.
NOTE: The Armbruster et al. 2006 paper on epidote nomenclature recommended that three members of the epidote group get renamed. One of these changes would be tweddillite (only discovered 5 years earlier), which was to be renamed manganipiemontite-(Sr). This fancy new name will look familiar when you watch the video. But these re-namings caused a huge uproar, in part because the powerful Franklin NJ mineral collector lobby (ha ha) preferred the original name of the epidote-group mineral that was to become epidote-(Pb). That original name was hancockite (named after a collector of Franklin minerals). After years of pressure, in 2015, the normally autocratic CNMMN finally relented and clinozoisite-(Sr) returned to niigataite, epidote-(Pb) returned to hancockite, and manganipiemontite-(Sr) returned to tweddillite (and the similarly horribly renamed apatite group minerals also returned to their former familiar names). Although this video was put together in 2017, you can ascertain that my Excel formulas must date back to sometime between 2006 and 2015 (ca. 2010, I believe), during the short lifetime of those chic but generally despised new names (and yes,
Frank will revert names in his spreadsheet eventually... He also has amphiboles [again] and pyrochlores to update... a mineralogist's bookkeeping efforts are seemingly never complete). In any case, when you get to "manganipiemontite-(Sr)" in the video, just replace it in your mind with the odd-sounding but original (and now reincarnated) "tweddillite"... named, incidentally, after the curator of a South African geological museum.
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