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They are a form of breccia, which is a textural term for any rock composed of angular fragments. [10] [11] Eye agates have circular banded spots on their surface. These "eyes" are actually hemispheres that form on the husk of the agate and extend inward like a bowl. Tube agates contain tunnel-like structures that extend all the way through the ...
The color of amethyst has been demonstrated to result from substitution by irradiation of trivalent iron (Fe 3+) for silicon in the structure, [4] [12] in the presence of trace elements of large ionic radius, [3] and to a certain extent, the amethyst color can naturally result from displacement of transition elements even if the iron ...
Widmanstätten pattern, metallographic polished section. Iron and nickel form homogeneous alloys at temperatures below the melting point; these alloys are taenite. At temperatures below 900 to 600 °C (depending on the Ni content), two alloys with different nickel content are stable: kamacite with lower Ni-content (5 to 15% Ni) and taenite with ...
Iron meteorites, also called siderites or ferrous meteorites, are a type of meteorite that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Most iron meteorites originate from cores of planetesimals, [3] with the exception of the IIE iron meteorite group. [4]
Liesegang rings (/ ˈ l iː z ə ɡ ɑː ŋ /) (also called Liesegangen rings or Liesegang bands) are colored bands of cement observed in sedimentary rocks that typically cut across bedding. [ 1 ] [ 2 ] These secondary ( diagenetic ) sedimentary structures exhibit bands of ( authigenic ) minerals that are arranged in a regular repeating pattern ...
Chromite and magnetite are ore minerals that form in this way. [1] Liquid immiscibility: sulfide ores containing copper, nickel, or platinum may form from this process. As a magma changes, parts of it may separate from the main body of magma. Two liquids that will not mix are called immiscible; oil and water are an example.
Mineralogy applies principles of chemistry, geology, physics and materials science to the study of minerals. Mineralogy [n 1] is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts.
Colorless beryls, also called goshenite, become pure yellow when irradiated, which are called golden beryl or heliodor. [1] Quartz crystals turn "smoky" or light gray upon irradiation if they contain an aluminum impurity, or amethyst if small amounts of iron are present in them; either of the results can be obtained from natural radiation as well.