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GeneralThree-pointed stars included
6th Nov 2018 05:48 UTCAndrea Oppicelli
These three-pointed star-shaped images are present as included in a phlogopite sample found in Ariccia (Rome-Italy): what can they be due to? Fov 3 mm.
6th Nov 2018 06:09 UTCPavel Kartashov Manager
12th Nov 2018 07:25 UTCAndrea Oppicelli
12th Nov 2018 13:52 UTCKevin Conroy Manager
12th Nov 2018 15:57 UTCKevin Hean
I think it is a microscopic gap or space between the Rutile and the Phlogopite that is refracting the light causing the iridescence,
I say microscopic because it appears blue ?
12th Nov 2018 20:46 UTCKevin Conroy Manager
12th Nov 2018 22:08 UTCEd Clopton 🌟 Expert
13th Nov 2018 05:33 UTCAndrea Oppicelli
These particular star images are just some air-filled channels between the phlogopite laminations. The different coloration I think is due to the angle of the light source.
But the star shape?
If the crystal of phlogopite has a hexagonal shape and we put many close together, we obtain a sort of honeycomb shape. The sides between 3 close crystals have just the shape of a 3-pointed star. Here is my simple hand-made drawing the explanation of this phenomenon. The growth of the individual crystals in the three phases and the subsequent delamination between the crystals with penetration of air formed these channels. Just with that shape due to the stepped division between the various crystalline laminae.
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