Question

Mica is classified under which category of cleavage due to its ability to be easily broken down into smooth surfaces?

• A. Perfect
• B. Poor
• C. Eminent
• D. Distinct

Answer 1

Answer:

C. Eminent

Cleavage in Minerals

Definition

Cleavage refers to the tendency of a mineral to break along specific planes of weakness in its atomic structure, resulting in smooth, flat surfaces. The nature of these planes determines the type of cleavage.

Classification of Cleavage

• Eminent (or Perfect) Cleavage: Minerals with eminent cleavage break very easily along one or more directions, producing exceptionally smooth and flat surfaces. Mica is a prime example of a mineral exhibiting eminent cleavage.

• Good Cleavage: Minerals with good cleavage break along distinct planes, but the surfaces may not be as perfectly smooth or flat as those with eminent cleavage.

• Fair Cleavage: Minerals with fair cleavage break along planes, but these are not as well-defined, and the resulting surfaces may be somewhat irregular.

• Poor Cleavage: Minerals with poor cleavage show only slight evidence of breaking along planes, and the surfaces are often rough and uneven.

• No Cleavage: Some minerals do not have any cleavage planes and break irregularly, a property known as fracture.

Mica and Eminent Cleavage

• Mica minerals (like muscovite and biotite) have a layered atomic structure.

• The bonds between these layers are very weak, allowing them to separate easily.

• This characteristic results in mica splitting into thin, flexible sheets, a clear indication of eminent cleavage.

• This property makes mica useful in various industrial applications where thin, insulating sheets are required.