Twin crystal

• Twinned crystal
• Symmetric crystal
• Flat diamond

Wiktionary Word definitions in Wiktionary
n. 1 (context mineral English) chiastolite; so called from the tessellated appearance of a cross-section. 2 (context mineralogy English) A crystal having a similar tessellated appearance. 3 (context mineralogy English) A twin crystal.

Wikipedia Word definitions in Wikipedia
Macle is a term used in crystallography . It is a crystalline form, twin-crystal or double crystal (such as chiastolite ). Macle is an old French word, a heraldic term for a voided lozenge (one diamond shape within another). Etymologically the word is derived ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Chiastolite \Chi*as"to*lite\ (k[-i]*[a^]s"t[-o]*l[imac]t), n. [Gr. chiasto`s marked with a [chi] + -lite. See Chiasm . So called from the resemblance of the cross cuts of its crystals to the Greek letter [chi].] (Min.) A variety of andalusite; -- called ...