Just in case some of you don't know what Hypertufa is (Thanks to Wikipedia)...

Hypertufa is an anthropic rock made from various aggregates bonded together using Portland cement.

Hypertufa is intended as a manufactured substitute for natural tufa, which is a slowly precipitated limestone rock; being very porous, it is favorable for plant growth.

Hypertufa is popular for making garden ornaments, pots and land forms. Hypertufa is relatively light compared with terracotta or traditional concrete and can withstand harsh winters, at least down to âÂÂ22F.

Aggregates are generally Sphagnum (peat moss), sand, and perlite or vermiculite. Hypertufa made with the classic proportions for mortar (1 part cement: 3 parts aggregate) has a composition of

3 parts Type I Portland cement

4 parts Sphagnum

5 parts perlite

or 3 parts cement: 9 parts aggregate[2]

To increase structural strength and longevity, polymer fibers, liquid acrylic, and fiberglass may be incorporated into the mixture. Powdered concrete dyes (in small amounts) tint the hypertufa to resemble natural rock.

A few photo examples:

http://www.pbs.org/wgbh/victorygarden/images/knowhow/pp/antiqueplanters/hypertufa_lg.jpg

http://s2.hubimg.com/u/86257_f520.jpg

http://www.hypertufagardening.com/2009/02/hypertufa-building-walkway-using.html