EDIT ADDED BY froggsong: This thread has been removed from the HabbaCrete review thread located here. Please click the link to go to the original thread if you are interested.
(from my research so far) habacrete is most likely a form of plaster (read page 3 for update)
pottery plaster is calcium sulfate hemihydrate , crystalline silica and 5% portland cement, pottery plaster is intended for repeat use for cast moldings of wet clay.
calcium sulfate hemihydrate is non toxic.
this 5% of portland cement is not enough to drastically change the ph run off of water, but enough to strengthen the plaster and give it a resistance to weather. i have done a 12 hour test with ph reading of water prior to soaking, and a long over night soak with another ph reading of the water. ph only raised one point. from 7 to 8, good soil will naturally correct this ph change as it is slight.
pottery plater has a 7-14 min work time being more or less depending on method of mixing and water to plaster ratio. habacrete also has the same work period.
habacrete indicates its ready for reptile use in less then 24 hours. pottery plaster takes about 30 min to fully set up and is fully dried out in about 24 hours as indicated by the label.
my testing indicates that habacrete if not pottery plaster, is some sort of plaster mix. habacrete is a plaster varrient mixed with an aggregate to create better texture and high build
this is my test of pottery plaster mixed with sand, and then wet washed with dark acrylic paint.
dont spend 10$ per pound and the headache of dealing with herpinvert. go to your local hobby store. hobby lobby carries this stuff under 2 different lables.

above it says plaster of paris, for molding. it is the same as pottery plaster as it has the same item number, it does infact say plaster of paris but it is the pottery plaster mix. i have contacted usg to verify all this information.
usg manufactures this product and it can be found in bulk online here.
Plaster.com - Pottery Plaster - USG® Pottery Plaster is great for all types of ceramic slip casting applications.
full data sheet of product and toxicology of it can be found here
http://www.anchsand.com/LinkClick.as...aster_MSDS.pdf
heres some other links related to herp invert
HerpInvert Brand Vivarium Supplies
if they weren't so difficult to deal with.... i would have bought the product and never investigated alternative routs instead.
edit: 3-26-2011
so you dont have to read teh whole thread. ... habacrete is activa' brand Perma-stone which can be ordered in large quantity from the distribution in northern texas. look on their website and call for more details
it can also be bought from michaels craft store.
it is about 1.50 a lb if you buy 7lb box of it in store. or about 1$ or less per pound if you order a huge bag of it. but shipping may be pricey.
it is non toxic and weather resistant it is also inert., it is a poly plaster which sets up with in 20 min. i did 4 coats in one hour and was finished in an hour. it does not contain gypsen so it will not break down in water. it will wear like any normal concrete will wear over time. weathering naturally .