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The stars are caused by the light reflecting from needle-like inclusions of rutile aligned perpendicularly to the rays of the star. The star-effect may be also caused by the inclusions of hematite . In black star sapphire hematite needles formed parallel to the faces of the second order prism produce asterism.
Note on Vertex figure images: The white polygon lines represent the "vertex figure" polygon. The colored faces are included on the vertex figure images help see their relations. Some of the intersecting faces are drawn visually incorrectly because they are not properly intersected visually to show which portions are in front.
Star polygon – there are multiple types of stars Pentagram - star polygon with 5 sides; Hexagram – star polygon with 6 sides Star of David (example) Heptagram – star polygon with 7 sides; Octagram – star polygon with 8 sides Star of Lakshmi (example) Enneagram - star polygon with 9 sides; Decagram - star polygon with 10 sides
Rutile is an oxide mineral composed of titanium dioxide (TiO 2), the most common natural form of TiO 2. Rarer polymorphs of TiO 2 are known, including anatase , akaogiite , and brookite . Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high ...
These images show each form with a single face colored yellow to show the visible portion of that face. There are also an infinite number of regular star dihedra and hosohedra {2,p/q} and {p/q,2} for any star polygon {p/q}. While degenerate in Euclidean space, they can be realised spherically in nondegenerate form.
In heraldry, a mullet is a star with straight arms and typically five points. A star with wavy rather than straight rays is called an estoile. [1] The mullet, used as an heraldic charge, is the ensign of knightly rank, and every order of knighthood incorporates this symbol in some way.
Glowing Eye Nebula or Dandelion Puffball Nebula: NGC 6751: 1863 6.5 11.9 Aquila: ... Download as PDF; Printable version; In other projects Wikimedia Commons; Wikidata ...
Chatoyancy is caused by either the presence of fibrous structures within the material, such as in tiger's eye quartz, or by fibrous inclusions and cavities, as seen in cat's eye chrysoberyl. In cat's eye chrysoberyl, the chatoyant effect is caused by the presence of rutile, composed mostly of titanium dioxide, which aligns perpendicularly to ...