Reply To: Mold, Cast and Steinkern

Homepage Forums What Is It? Mold, Cast and Steinkern Reply To: Mold, Cast and Steinkern

John Christian

Thanks Benjamin,

So to simplify, a cast is made only against a mold. Right? A mold is only made by direct contact with the original fossil. Correct?  Therefor my steinkern is an internal mold since it formed against the original shell… right?

I am a little confused by your use of “positive” and “negative” in reference to impressions. Does “positive” and “negative”  refer to concave and convex? If “negative = cast” then the definition of a “mold” would be a: mold impression of the original formed by contact with the original. That is a confusing definition.

If “negative” = mold = convex, then some molds break that rule. A steinkern which can be an interior mold is convex in most bivalves. Exterior molds are usually concave but are partly convex when the original bivalve has a concave valve (some pectens and brachiopods.)

Thanks for you help.