Is Opal a crystal like Quartz? Nope! It’s got “crystalised water in it”. WOW
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth’s continental crust, behind feldspar. Quartz comprises more than 10% by mass of the earth’s crust!
Opal really made up of little Silica Spheres?
It lacks the characteristic of a crystal
Practical Demo ….
Opal color is formed in the internal structures of precious Opal. Precious Opal will diffract light creating a spectrum of colours whereas potch has no diffraction and no opal color. Scientifically precious opal is known as SiO2·nH2O. Opal is made up of tightly packed minute silica spheres only 0.00001 inches’ wide. If these spheres are aligned correctly and just the right size they will produce flashes of opal colour. If they are randomly sized and arranged they will be called potch.
Opal is a hydratedamorphous form of silica (SiO2·nH2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%.
Opals are precious multi-coloured gemstones made primarily of silica.
How does the colour form? Lets watch the video…
Scientists admit that much of the chemistry is not well understood.