Biominerals (pearls): What are the principal constituents of natural pearls? Identify the mineral phase and the organic matrix secreted by molluscs. Choose the correct pair.
General Knowledge
General Science
Difficulty: Easy
Choose an option
Answer
Correct Answer: Aragonite and conchiolin
Explanation
Given data
- Object: Natural pearls (nacre).
Concept/ApproachPearls consist mainly of aragonite (a crystalline form of CaCO3) arranged in platelets, bound by an organic protein–polysaccharide matrix called conchiolin.
ReasoningAragonite (mineral) + conchiolin (organic) → nacre's layered structure and luster.
Common pitfallsConfusing aragonite with calcite (another CaCO3 polymorph) or pairing with unrelated salts.
Final AnswerAragonite and conchiolin