Very thin laminae of haematite, blood-red by transmitted light, occur as microscopic enclosures in certain minerals, such as carnallite and sun-stone, to which they impart colour and lustre.
Among the trees are several which yield excellent timber, such as the tacula (Pterocarpus tinctorius), which grows to an immense size, its wood being blood-red in colour, and the Angola mahogany.
High, with drooping blood-red blossoms, is now referred to the genus Dierama.
I have seen at one time lying on the ice pickerel of at least three different kinds: a long and shallow one, steel-colored, most like those caught in the river; a bright golden kind, with greenish reflections and remarkably deep, which is the most common here; and another, golden-colored, and shaped like the last, but peppered on the sides with small dark brown or black spots, intermixed with a few faint blood-red ones, very much like a trout.
Thus, when a strong light is viewed through a solution of chlorophyll, the light seen is a brilliant green if the thickness is small, but a deep blood-red for thicker layers.
Brown or even blood-red stripes have been observed in the North Atlantic when swarms of the copepod Calanus finmarchicus were present; the brown alga Trichodesmium erythraeum, as its name suggests, can change the blue of the tropical seas to red; swarms of diatoms may produce olive-green patches in the ocean, while some other forms of minute life have at times been observed to give the colour of milk to large stretches of the ocean surface.
He waited while she rolled up her sleeve in excitement, then displayed the blood-red tattoo there.