However, most white crystals contain ice cracks, clouds and other connotations. Unless the completely transparent white crystal is very small (directly cut and ground from the raw ore), the large completely transparent white crystal is more expensive and there are many fakes on the market. So be careful when you buy it.
2. Pure water. Water is a colorless and odorless liquid, and 72% of the earth's surface is covered with water. Although there is little water in the air, it is an important part of the air. The density of solid water (ice) (9 16.8kg/m3) is less than that of liquid water (999.84kg/m3), so the ice will float on the water surface, and the volume of water will increase slightly when it freezes.
Water reaches its maximum density (999.97 kg/m3) at 3.98℃, while the maximum density of other liquids appears at the melting point. Water molecules are polar, that is, the positive and negative charge centers of water molecules do not coincide, which makes water a good solvent.
3. Permeable glass. Ordinary glass is an amorphous solid with irregular structure (from a microscopic point of view, glass is also a liquid), and its molecules are not arranged in a long-range order in space like crystals, but in a short-range order like liquids. Glass keeps a certain shape like a solid, unlike liquid, which flows by gravity.
Extended data:
Optical transmission principle
There are three kinds of interactions between light and matter: (1) light is reflected (2) light is absorbed by matter (3) light passes through matter.
The necessary condition for the formation of transparent body is not to absorb or reflect all visible light. The principle of this effect lies in whether the aggregation structure of matter is isotropic or anisotropic.
If the aggregate structure of matter is isotropic, then all the light can pass through, but not all reflected or absorbed, that is, transparent; On the other hand, if the aggregate structure of matter is anisotropic, then the light cannot completely pass through and be reflected or absorbed, that is, it is opaque.
Glass is amorphous and its molecular aggregation structure is isotropic, so light can pass through it, so it is transparent. Common iron, because it is crystal, its aggregate structure is anisotropic, so light cannot pass through smoothly, so it is opaque.
If molten iron is rapidly cooled so that it does not crystallize during rapid cooling, its aggregate structure becomes isotropic, and it can also be made into transparent iron in theory. However, it is not possible yet.
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