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Chalcocite (/ ˈ k æ l k ə ˌ s aɪ t /), [6] [7] copper(I) sulfide (Cu 2 S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system. The term chalcocite from the Greek khalkos, meaning "copper".
As a significant product of copper mining, copper(II) oxide is the starting point for the production of many other copper salts. For example, many wood preservatives are produced from copper oxide. [3] Cupric oxide is used as a pigment in ceramics to produce blue, red, and green, and sometimes gray, pink, or black glazes. [3]
A copper nanoparticle is a copper based particle 1 to 100 nm in size. [1] Like many other forms of nanoparticles , a copper nanoparticle can be prepared by natural processes or through chemical synthesis. [ 2 ]
The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word suspension is distinguished from colloids by larger particle size). A colloid has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension).
Grey or white hair is not caused by a true grey or white pigment, but is due to a lack of pigmentation and melanin. The clear hairs appear as grey or white because of the way light is reflected from the hairs. The change in hair colour occurs when melanin ceases to be produced in the hair root and new hairs grow in without pigment.
Black for copper. Solution of sodium polysulfide 2.5%, items must be submerged in the solution after color developing, wash, dry and wax or varnish colored object. [27] Brown for copper. Items are boiled in at least 3-day-old water solution of 12% copper sulfate, after color being developed, the material is washed, dried and waxed or varnished ...
Schematic representation of the different stages and routes of the sol–gel technology. In this chemical procedure, a "sol" (a colloidal solution) is formed that then gradually evolves towards the formation of a gel-like diphasic system containing both a liquid phase and solid phase whose morphologies range from discrete particles to continuous polymer networks.
Premature greying of hair has been observed with greater frequency among certain families, suggesting a familial predisposition for the condition. As hair pigmentation is a result of complex interaction between various genetic factors, it is thought that premature greying could be due to exhaustion of melanocyte 's capability to produce hair ...