The only naturally occurring bentorite that has been discovered is in the Hatrurim Formation near the Dead Sea in Israel. The formation consists of a mixture of
metamorphosed clays,
limestones, and
marls. The original sediments were enriched in chromium, and later experienced heating to >1000 °C at atmospheric pressure. This formed a natural
Portland cement which has since been hydrated from
groundwater and/or
rainwater to form a natural
concrete. The source of the heat is thought to be due to
combustion of
coal,
oil, or
gas. Following this combustion metamorphosis, highly alkaline fluids penetrated and altered the rock to form
supergene veins of bentorite. == Applications ==