Which material is described as a mineraloid despite resembling a mineral?

Understand the Problem

The question is asking about a specific type of material known as a mineraloid, which is something that resembles a mineral but does not meet all the criteria to be classified as one. The task involves identifying which of the provided options fits this description.

More Information

Opal is considered a mineraloid because it lacks a crystalline structure, which is a key characteristic of minerals.

Sources

• Minerals - Tulane University - .tulane.edu
• Mineraloid - Wikipedia - en.wikipedia.org
• What is a Mineraloid? Definition, photos and descriptions - geology.com