Dear Tony:
The MINERAL Database could give you references:
e.g. for hydrotalcite: Min. Mag. 39 (1973), p.377
Benyam Estifanos, PhD
Dept. of Mineralogy & Petrology
University of Lund
Soelvegatan 13
SE-223 62 Lund, Sweden
INTERNET: estif@gemini.ldc.lu.se
Tel.:+46 46 2224597; Fax:+46 46 121477