Which term describes a crystal consisting of two or more parts formed in a symmetrical manner with shared crystal planes?

Which term describes a crystal consisting of two or more parts formed in a symmetrical manner with shared crystal planes?

• A. Unit Cell
• B. Vacancy
• C. Twinned Crystal
• D. Trace Elements

Answer: (C)

Crystal twinning is when two or more parts of a crystal form in a symmetrical relationship and share crystal planes. A twinned crystal is literally made of these mirrored parts bound together along a twin plane, which is why this term fits perfectly. The other options describe different things: a unit cell is just the smallest repeating portion of the lattice, not a multi-part assembly; a vacancy is a missing atom in the lattice; trace elements are tiny impurities within the crystal.

Crystal twinning is when two or more parts of a crystal form in a symmetrical relationship and share crystal planes. A twinned crystal is literally made of these mirrored parts bound together along a twin plane, which is why this term fits perfectly. The other options describe different things: a unit cell is just the smallest repeating portion of the lattice, not a multi-part assembly; a vacancy is a missing atom in the lattice; trace elements are tiny impurities within the crystal.