Question

In the Bowen's reaction series, which of the following mineral(s) is/are crystallized prior to amphibole?
A. Biotite
B. Clinopyroxene
C. K-feldspar
D. Forsterite

• A. A and B only
• B. A, B and D only
• C. B only
• D. B and D only

Hint:

Remember the order of the discontinuous series: Olivine -> Pyroxene -> Amphibole -> Biotite. A mnemonic could be "Old Pilots Are Boring".

Answer 1

The Correct Option is D

Step 1: Understand the discontinuous branch of Bowen's reaction series.This series details the crystallization temperatures of silicate minerals from cooling magma, with the discontinuous series focusing on ferromagnesian minerals.

Step 2: Order the minerals in the discontinuous series by decreasing crystallization temperature.The order is:1. Olivine (e.g., Forsterite, D) - Highest Temperature2. Pyroxene (e.g., Clinopyroxene, B)3. Amphibole4. Biotite mica (A) - Lowest Temperature

Step 3: Determine which minerals crystallize before amphibole.Olivine (Forsterite) and Pyroxene (Clinopyroxene) crystallize before amphibole.

Step 4: Examine other minerals.- Biotite (A) crystallizes after amphibole.- K-feldspar (C) from the continuous branch crystallizes at lower temperatures than amphibole.Conclusion: Clinopyroxene (B) and Forsterite (D) crystallize before amphibole.