Cadmium cinnabar

This is a cadmium mercury sulfide q.v.) pigment, analogous to cadmium cinnabar, of orange to red hue (de Keijzer, 1990). 

The principal red and yellow pigments are Lead chromate chrome yellow, orange and red), zinc chromate zinc or buttercup yellow), barium chromate lemon yellow or yellow ultramarine) various products based on jerric oxide, hydrated (yellow) or anhydrous (red), both natural yellow and red ochres) and artificial Mars yellow, English red, etc.) red oxide oj lead minium or red lead) mercuric sulphide cinnabar, vermilion) antimony oxysulphide antimony cinnabar) cadmium sulphide cadmium yellow) basic lead antimonate Naples yellow). 

It may contain, as impurities or as additions, other cadmium compounds, zinc compounds and free sulphur, and it may also be adulterated with chrome yellow, cinnabar, arsenic sulphide, heavy spar and gypsum. 

The alkaline earth group as a whole stands in marked contrast to transition metals and post-transition metals. For example, most of the metals in the periodic table form insoluble precipitates with the sulfide ion (S2), with the result that sulfide ores of transition and post-transition metals are very common in Earths crust. Common examples of metal sulfides include galena (lead sulfide), cinnabar (mercury sulfide), gree-nockite (cadmium sulfide), acanthite (silver sulfide), cobaltite (cobalt arsenic sulfide), sphalerite (ZnS), stibnite (antimony sulfide), several copper sulfides, orpiment and realgar (both forms of arsenic sulfide), and pyrite (iron sulfide). None of the alkaline earths, however, are found as sulfides. 

The mercury sulfide compounds are undoubtedly the most important of the mercury group pigments as they include the red mineral cinnabar (HgS) and its synthetic analogue mercury(ll) sulfide, commonly known as vermilion q.v.). Two other crystal modifications of mercury(ll) sulfide occur, the hypercinnabar tyqie (P-HgS) and the metacinnabar type (a -HgS), the latter primarily significant as a black alteration product. Additionally, cadmium mercury sulfide ((Cd,Hg)S) is relevant in the context of cadmium sulfide pigments. 

Cadmium sulfides and selenides group Mercury group Cadmium mercury sulfide Cinnabar Hypercinnabar Mercury(ll) sulfide, cinnabar type Mercury(ll) sulfide, metacinnabar type Vermilion... 

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