The colour of anhydrous ferric chloride is

deep red

Ferric chloride colour: The colour of anhydrous ferric chloride varies based on the crystalline structure and the angle of light. Ferric chloride is a common compound of iron in the +3 oxidation state, and its appearance is influenced by these factors. Here's a more detailed breakdown of its characteristics:

• Crystalline Appearance: Anhydrous ferric chloride, when in its solid form, typically appears as a dark green colour. However, it has a unique optical property where the hue can change depending on the viewing angle.
• Light Reflection and Transmission: When light is reflected off the crystals, ferric chloride exhibits a dark green colour. On the other hand, when the crystals transmit light, they appear to have a purple-red tint. This difference in appearance is due to the different ways the crystalline structure interacts with light.
• Melting Point and Physical Properties: The melting point of anhydrous ferric chloride is 307.6 °C. Its physical properties, along with its interaction with light, contribute to the distinctive changes in colour depending on how it is viewed.

Based on the crystalline nature and the way light is reflected or transmitted through ferric chloride, its colour can range from dark green to purple-red.