CRYSTAL FORMATION AND THE PIEZOELECTRIC EFFECT
This will appeal to some and maybe not others – but hey if we really really like crystals we should perhaps understand where they come from and how they are formed I guess. This an extremely brief explanation…
Crystals are like a chemical imprint for evolution – the earths DNA. Each type of crystal is solid, geometrically regular and unique - each type will have the same internal structure. Whilst each type of crystal may be coloured differently, their internal structure will be identical – and this is how they are identified. Crystals ultimately were born in the molten ball that formed the earth and have undergone metamorphoses in line with changes in the planet. The conditions for crystal formation is temperature, pressure, space and time. The earths’ crust consists on the whole of silicon and oxygen along with aluminum, iron, sodium, potassium, calcium and magnesium, and from this we see the formation of splendid shapes, varieties and colours of all the different crystals. It is said that changes in the planet are recorded in crystals – storing all the earths changes. In fact the earth is 85% crystal. There are 7 geometric forms – these are square, triangle, rectangles, parallelograms, rhomboids and trapeziums. These lock together and form the crystal shapes we see. For example a group of squares would form a cubic crystal. One of the specialities of crystals is the piezoelectric effect – some crystals can convert mechanical pressure into electrical energy which can then be subsequently converted into precise mechanical vibrations. This happens when pressure is applied to quartz crystals and the lattice becomes temporarily deformed. More specifically there is polarisation within the crystal – with the positive silicon ions moving to one side of the crystal and the negative ions to the other side. The opposing sides then develop powerful and differing electrical charges. However due to the fact that crystals are non-metallic and they do not have loose electrons they are incapable of producing electric currents. Thus this renders them unusable in industry for this purpose and therefore synthetic Piezoelectric crystals have to be laboratory produced. However these synthetic crystals have the same atomic structure and properties as natural crystals. Public Domain, https://commons.wikimedia.org/w/index.php?curid=157164
|
A UNIQUE and showy combination specimen from recent finds at the Wudong Mine of China. A gemmy and lustrous, 8 mm, bi-colored, tan and colorless, apatite crystal sits front and center on cherry-red rhodochroite rhombs, purple fluorite cubes, quartz and a dusting of brass-yellow pyrite cubes. Certainly an unusual and rare specimen from this up and coming locality.
Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons A specimen consisting of a bornite-coated chalcopyrite crystal nestled in a bed of clear quartz crystals and lustrous pyrite crystals. The bornite-coated crystal is up to 1.5 cm across.
Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons |