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This is a list of substances or materials generally considered discredited. A substance can be discredited in one of three ways: It was widely believed to exist at one time but no longer is. Such substances are often part of an obsolete scientific theory. It was once believed to have drastically different properties from those accepted now.
Use of old mineral names is also discontinued, for example when a name is no longer considered valid. Therefore, a list of recognised mineral species is never complete. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species.
The Fitzpatrick scale has been criticized for its Eurocentric bias and insufficient representation of global skin color diversity. [9] The scale originally was developed for classifying "white skin" in response to solar radiation, [2] and initially included only four categories focused on white skin, with "brown" and "black" skin types (V and VI) added as an afterthought.
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 February 2025. "Skin pigmentation" redirects here. For animal skin pigmentation, see Biological pigment. Extended Coloured family from South Africa showing some spectrum of human skin coloration Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among ...
Human blood in veins is not actually blue. Blood is red due to the presence of hemoglobin; deoxygenated blood (in veins) has a deep red color, and oxygenated blood (in arteries) has a light cherry-red color. Veins below the skin can appear blue or green due to subsurface scattering of light through the skin, and aspects of human color ...
The claim that applying minerals directly to the skin in the form of cosmetics has health benefits, however, has inspired some scientific controversy. [3] Historically some mineral additives have proven to be poisonous to the skin, such as lead. [4] and the mineral Bismuth that can cause a negative skin reaction. However the kinds of minerals ...
Mineral makeup most commonly refers to a foundation in loose powder format. The most common minerals used as the base are mica, bismuth oxychloride, titanium dioxide, or zinc oxide. However, talc is also a mineral, so a talc-based powder could be considered a "mineral makeup"—although most mineral makeup sold makes a point of being talc-free ...
Olive skin is a human skin tone. It is often associated with pigmentation in the Type III, [ 1 ] [ 2 ] Type IV, and Type V ranges of the Fitzpatrick scale . [ 3 ] [ 4 ] It generally refers to moderate or lighter tan or brownish skin, and it is often described as having tan, brown, cream, greenish, yellowish, or golden undertones.