sentence: Red cinnabar is used for the pigment vermilion.
sentences_before: Cinnabar' is a mineral. Cinnabar exists in two crystal forms.
sentences_after: It is poisonous, and may go black with age. The other crystal form is black, and does not react chemically to anything except strong acids. Cinnabar has a Mohs hardness of 2-2.5.
concept_name: red cinnabar
headings: Cinnabar
categories: Minerals Ores