Been doing research of Ariocarpus in their natural habitat to find out what soils/minerals they grow in.
Found out that they grow in Limestone hills and gypsum flats.

So I revised I mix which will give them the nutrients they receive from their habitat.
This here's my mix;
Pumice – 1 part
Crushed Limestone or Dolomite of Lime 1-3mm (substitute for scoria) – 1 part
Gypsum - 1 part
Clay – 1 part
Zeolite – Top dressing
Slow release fert

The zeolite isn't necessary but I thought if I could find it I'll use it.
Do I need scoria or will the crushed limestone be a suitable enough substitute?
I put clay in so that it can hold a bit of nutrients that will be available to the roots.

Any input would be nice. I wasn't sure about how much I should add of each thing also. Thought 1 part of each seemed balanced.
Mitch.

Looks good to me mate. I think the limestone is a good addition but I'm not sure how it will go over time, it may turn to fine sand and slowly be watered out. I feel scoria is a good addition to any cacti mix but you certainly don't need it.

One other minor issue is the clay, firstly I don't think you need it (Ario roots are very good at extracting nutrients) and the gypsum will break the clay down where it will be watered out over a very short period.

That being said I have never used either ingredient I'm just basing this on my knowledge of each.

HN

Makes sense to me. I'll get rid of the clay.
I kind of want the limestone to break down because that's the only real way the Ario can get the nutrients from it. I'm sure if it starts breaking down I would have repotted it and with new a mix before the limestone breaks down anyway.
I think its important to replicate as best as I can what plants grow in in habitat. The plants suited to that habitat for a reason so I think its best to replicate what soil it grows in.
Adding limestone just might be the key to "fast" growing Arios.
Minus the clay do you think the proportions are pretty alright?

I'm getting my propagating unit set up and I've bought my seeds.
Should I be growing the seeds in 100% coarse sand, 50-50 sand and vermiculite or should I add expanded clay granules?
Will post pics when my seeds germinate.

Can't wait to see them!