Question

Which of the following options represent(s) simultaneous crystallization of two minerals in the given feature(s)?

• A. Granophyric texture
• B. Myrmekite
• C. Corona of orthopyroxene around anhedral olivine
• D. Cumulate pyroxene with interstitial plagioclase

Hint:

Intergrowth textures like graphic, granophyric, and myrmekitic are good indicators of simultaneous crystallization of two minerals. Reaction rims (coronas) and cumulates represent sequential crystallization instead.

Answer 1

The Correct Option is A, B

Step 1: Recall the concept of simultaneous crystallization.
When two minerals crystallize together in mutual interference patterns or intergrowths, it indicates simultaneous crystallization from a melt.

Step 2: Check each option.
- (A) Granophyric texture: This is an intergrowth of quartz and feldspar with graphic or suture-like contacts, typical of simultaneous crystallization → Correct.
- (B) Myrmekite: Wormy intergrowth of quartz in plagioclase, formed due to reaction or simultaneous growth → Correct.
- (C) Corona of orthopyroxene around olivine: Represents a reaction rim texture, not simultaneous crystallization.
- (D) Cumulate pyroxene with interstitial plagioclase: Indicates sequential crystallization, not simultaneous.

Step 3: Conclusion.
The correct examples of simultaneous crystallization are (A) and (B).

Final Answer: \[ \boxed{\text{(A) Granophyric texture and (B) Myrmekite}} \]