Ok. Sometimes "crazy" pays off...
I was really getting curious as to what Reefceramics was made of, and was having a hard time pinning anything down.
So I headed to Wiki, and spent some time following links. Keeping "calcium" in mind, I read through "ceramics", and ended up at "alabaster".
If one goes to the "Porcelain" article, under "European Porcelain", it says:
"...a combination of ingredients, including Colditz clay (a type of kaolin), calcined alabaster and quartz."
Reading the "Alabaster" article, came up with this gem:
"The coarser varieties of alabaster are converted by calcination into plaster of Paris, whence they are sometimes known as "plaster stone.""
If this were being done with limestone, you could make cement, if you follow where I am trying to go with this.
If you are following, you need to have your head examined, lol.
Anyway.
Both Plaster of Paris and Alabaster are high in calcium. One is gypsum based, the other limestone based, to grossly simplify.
I was thinking that reefceramics are either white portland, (which is both gypsum and limestone based - all cement is both, but white has a lot more gypsum than grey does) that is being fired like a brick to (possibly) eliminate the 4-8 week curing period (because if you read, reefceramics still needs to kure for a week or two), or is plaster of paris based or alabaster porcelain based.
Or maybe it's the weird b@$+@?|) love-child of white cement and either of the other two.
But I then googled "cement magnesium", and found something called "eco-cement". A great, but simple article on eco-cement can be found here:
http://www.tececo.com/simple.eco-cement.php
So maybe reefceramics are made of this "Eco-Cement", or a combination of something mentioned above. In reading this article, you could see where folks might run into trouble down the road, and how "detritus sink" could be used to describe them by folks experiencing problems.
I just wanted to share that - maybe that will give
Granny something to ask the "old-timers" about or one of you might think of something.
I hate being a curious monkey...