Question

In Bowen's Reaction Series, which mineral is the first to crystallize in the discontinuous series?

• A. Quartz
• B. Muscovite
• C. Olivine
• D. Biotite

Hint:

Remember the sequence using: \textbf{O}ld \textbf{P}eople \textbf{A}lways \textbf{B}ring (Olivine, Pyroxene, Amphibole, Biotite).

Answer 1

The Correct Option is C

Concept: Bowen's Reaction Series explains the sequence in which minerals crystallize from a cooling magma. It is divided into two branches:

• Discontinuous series: Minerals change structure as temperature decreases (Olivine $\rightarrow$ Pyroxene $\rightarrow$ Amphibole $\rightarrow$ Biotite).
• Continuous series: Plagioclase feldspar evolves gradually from calcium-rich to sodium-rich composition.

The discontinuous series is called so because each mineral has a different crystal structure and forms at different temperature ranges.
Step 1:Identify the highest temperature mineral in the discontinuous series.
Minerals crystallize from magma as it cools, with high-temperature minerals forming first.
Step 2:Recall the order of the discontinuous series.
\[ \text{Olivine} \rightarrow \text{Pyroxene} \rightarrow \text{Amphibole} \rightarrow \text{Biotite} \]
Step 3:Determine the first crystallizing mineral.
Olivine forms at the highest temperature and is therefore the first mineral to crystallize in the discontinuous series.