Prehnite Yellow

Prehnite

Prehnite is an inosilicate of calcium and aluminium with the formula: Ca2Al(AlSi3O10)(OH)2 with limited Fe3+ substitutes for aluminium in the structure. Prehnite crystallizes in the orthorhombic crystal system, and most often forms as stalactitic, botryoidal, reniform or globular aggregates, with only just the crests of small crystals showing any faces, which are almost always curved or composite. Very rarely will it form distinct, well-individualized crystals showing a square-like cross-section, including those found at the Jeffrey Mine in Asbestos, Quebec, Canada and China. Prehnite is brittle with an uneven fracture and a vitreous to pearly luster. Its hardness is 6.5, its specific gravity is 2.80–2.95 and its color varies from light green to yellow, but also colorless, blue, pink or white. In April 2000, rare orange prehnite was discovered in the Kalahari Manganese Fields, South Africa. Prehnite is mostly translucent, and rarely transparent.

Yellow

Yellow is a color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575–585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photo damage in some cases. Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths.

prehnite

Noun

1. A mineral, a basic calcium, aluminium and iron aluminosilicate, which occurs in stalactitic aggregates or curved crystals, Ca2Al2Si3O10(OH)2.

yellow

Noun

1. The color of sunflower petals and lemons; the color obtained by mixing green and red light, or by subtracting blue from white light; the color evoked by light of wavelength around 580 nm; one of the three primary colors in subtractive color systems.
2. The middle light in a set of three traffic lights, the lighting of which indicates that drivers should stop short of the intersection if it is safe to do so.

Adjective

1. Of a yellow hue.
2. Lacking courage.