Amazing Pottery

What is the clay that can be used for pottery that has the least amount of silica?

We're having this Investigatory Project wherein we're using mussel shells in place of silica in ceramic production; so we need a type of workable clay that has the least amount of silica as possible. And can anyone give me an example of a ceramic recipe? One involving clay, not the ones with salt, flour and all that stupid stuff. =)))))))) Thanks. :D

Public Comments

1. I have a couple of serious problems with your request. The first is that mussel shells are mostly made of calcium carbonate, not silica. http://en.wikipedia.org/wiki/Mussel#General_anatomy . In fact, shells were used as a source of calcium in making glass which the majority of the glass coming from silica in sand. The second is that silica in the form of feldspar http://en.wikipedia.org/wiki/Feldspar is basic to the structure of clay, forming the flat structures that allow the particles to slide past each other and yet adhere for forming. When clay is mixed from various sources to give various properties, some of the ingredients are flux, but many of them are various sized particles of clay, all containing silica.
2. Your doing ceramic production and you don't know anything about clay recipes? Or was the word production an error? To me that means manufacturing or small scale production. With out knowing what you are making and what temp you are firing to it is hard to give you a recipe, there are literally hundreds or thousands and people mix them to meet the needs of their work, like raku, dishes, high & low fire & so on.