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  2. Chemical impurity - Wikipedia

    en.wikipedia.org/wiki/Chemical_impurity

    An example of when impurities are wanted is shown in gems. These gems have slight impurities that act as chromophores and give the stone its color. An example is the gem family beryl which has the base chemical formula of Be 3 Al 2 (SiO 3) 6. Pure beryl will appear colorless but this rarely occurs and the presence of trace elements change its ...

  3. Contamination - Wikipedia

    en.wikipedia.org/wiki/Contamination

    Within the sciences, the word "contamination" can take on a variety of subtle differences in meaning, whether the contaminant is a solid or a liquid, [3] as well as the variance of environment the contaminant is found to be in. [2] A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process. [2]

  4. Liquidus and solidus - Wikipedia

    en.wikipedia.org/wiki/Liquidus_and_solidus

    Liquidus and solidus are mostly used for impure substances (mixtures) such as glasses, metal alloys, ceramics, rocks, and minerals. Lines of liquidus and solidus appear in the phase diagrams of binary solid solutions , [ 2 ] as well as in eutectic systems away from the invariant point.

  5. List of purification methods in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_purification...

    Electrolysis refers to the breakdown of substances using an electric current. This removes impurities in a substance that an electric current is run through; Sublimation is the process of changing of any substance (usually on heating) from a solid to a gas (or from gas to a solid) without passing through liquid phase. In terms of purification ...

  6. Mixture - Wikipedia

    en.wikipedia.org/wiki/Mixture

    It's an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proportion. [1] A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions or colloids. [2] [3]

  7. Bacteria and 'mold-like' substance found at Tom's of Maine ...

    www.aol.com/bacteria-mold-substance-found-toms...

    An FDA inspection of a Tom’s of Maine manufacturing facility led to the discovery of “significant violations,” including bacteria in water used to make toothpaste and a black “mold-like ...

  8. Brown snow fell in a Maine town. Here's what officials say ...

    www.aol.com/news/brown-snow-fell-maine-town...

    Officials warned residents not to touch the substance after initially saying some of the snow measured a pH level of 10, making the substance an alkali and a skin irritant. The Maine Department of ...

  9. For example, a product removed from the market due to tampering, without evidence of manufacturing or distribution problems, would be a market withdrawal." Medical device safety alert: ...