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This bundle checked and uploaded 23-01-2022 by ecrg.

Date should be repeated in:
- headers of axfiles for tc350 and above
- header of "igneous_set_full_descriptions.txt"
- name of directory
--- also change the webpage flag!
--- update benchmarks?
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Version notes:

Other than the changes listed below, the x-eos in these files 
are those in Tim Holland's web distribution, April 2019.
The April 2019 distribution corrected a small problem in the 
original 2018 web distribution accompanying the Holland, Green
& Powell (2018) paper. Some of the parameters for silicate melt
were inconsistent across the various axfiles found in the 2018 
distribution, though the effect on calculations was tiny.


%% ---- Changes since April 2019


% -- 07-20 en-odi modification
The July 2020 distribution makes small changes to the values of
two parameters in the orthopyroxene x-eos: 
  W(en,odi) becomes 29  0   0.15
  delG(tran,odi) becomes 1.9  0  0.005.
Ensures that an opx solvus must always be metastable with respect
to the cpx-solvus, as well as cpx-opx 
Attempting (unsuccessfully) to remove the tendency for a stable 
high-Ca opx to form in calculations on peridotite bulk compositions. 


% -- 10-20 Modifications to pyroxenes.

  1) Changes to parameters in pyroxene quadrilateral (end-members en, cen,
     odi, di, cfm, fm, cfs, fs in cpx and opx) to achieve:
     - Opx solvus always metastable with respect to the cpx solvus and 
       opx-cpx equilibria, over a relevant P,T range.
     - For the dependent hedenbergite end-member, G(hed,cpx)~G(hed,dataset) 
       and G(hed,cpx) < G(hed,opx) over a relevant P,T range.
     - Reductions to pressure dependencies where possible.

  2) Modifications to parameters associated with Ti-bearing end-members 
     obuf, cbuf. These are no longer treated as mixing ideally. This change
     appears to kill the stable high-Ca opx.

  3) Adjustment to W(jd,kjd) and delG(kjd,make) to avoid having too much 
     K in cpx at low P in Na,K-rich compositions.


% — 01-22 Add the new ternary feldspar x-eos from Holland Green Powell (2021).

   The pl4tr x-eos now replaces pli and plc. It is written in terms of 
       compositional variables xCa and xK. 
   Alternatively, use k4tr, which is identical to pl4tr except written in
       terms of xCa and xNa (therefore replacing ksp).