clay - http://www.thechocolatelife.com/clay/
I've been told by some sellers of bicolor seeds (unfermented) that they are also used in tejate, though I have yet to find a tejate vendor who admits to using it - cacao blanco they call it here.
A few weeks ago, I had occasion to "discover" this cacao blanco when I asked about at the Sunday Tlacolula market. I bought some and roasted it, then bought more later at the central de abastos. They make a wonderful nutty tasting roasted snack, that, if roasted right, you can sometimes peel by hand. They require more roasting than theobroma cacao, and the skin is thicker.
I also ground some up using my champion juicer. This works great with cacao, actually turning out a decent liqueur through the fine screen, and pushing what remains of the skins/husks (I'm still not very good at winnowing) through. With the bicolor, the fat seems to be denser and with a higher melting point. Running it through the champion juicer was much harder than with cacao. It would not go through the fine screen. Maybe I needed to run it through a couple more times, I don't know. Anyway, I've been making a delicious hot chocolate with some fine "almendra blanca" criollo beans from Tabasco, and in my latest pot, I included about 15% bicolor. It's delicious! Very buttery and creamy, and mildly nutty. I've also tried making a "hot chocolate" with only bicolor, and that's also delicious, though it tastes not at all of chocolate.
So much fun experimenting!...
I spent a few weeks in Oaxaca tasting and making hot chocolates. I wrote up several articles about my experiences on my blog Ultimate Hot chocolate (www.ultimatehotchocolate.com).
I found without my difficulty local women who taught me a variety of ways to make different locally loved hot chocolates. Everyone here drinks hot chocolate and it is an important part of big cultural events such as weddings etc. So groups often come together to make family recipes the traditional way.