Twin Law

Question 1

Contact

Answer 1

Braveno Law in Orthoclase {021}

Question 2

Polysynthetic

Answer 2

Albite Twin Law {010} in Plagioclase

Question 3

Cyclical

Answer 3

Chrysoberyl {031}

Question 4

Penetration

Answer 4

Carsbad Law in Orthoclase [001]

Question 5

Triclinic: Albite Law

Answer 5

{010} - polysynthetic

Question 6

Triclinic: Pericline Law

Answer 6

[010] – tartan twinning in microcline

Question 7

Monoclinic: Manebach Law

Answer 7

{001} (Orthoclase - contact twin)

Question 8

Monoclinic: Carlsbad Law

Answer 8

[001] (Orthoclase - penetration twin)

Question 9

Monoclinic: Braveno Law

Answer 9

{021} (Orthoclase - contact twin)

Question 10

Monoclinic: Swallow Tail Twins

Answer 10

{100} (Gypsum)

Question 11

Orthorhombic System

Answer 11

{110} Cyclical Twins - Aragonite, Chrysoberyl, Cerrusite

Question 12

Orthorhombic

Answer 12

Staurolite Law - {031} (Right-angle cross), {231} (~60° cross)

Question 13

{011} Cyclical Twins - Rutile, Cassiterite

Answer 13

Tetragonal

Question 14

Hexagonal System: Calcite Twins

Answer 14

{0001}, {012} (Polysynthetic twinning due to deformation)

Question 15

Hexagonal: Quartz Twins - Brazil Law

Answer 15

{110} (Penetration twin - transformation)

Question 16

Hexagonal: Quartz Twins - Dauphiné Law

Answer 16

[0001] (Penetration twin - transformation)

Question 17

Hexagonal: Quartz Twin - Japanese Law

Answer 17

{112} (Contact twin - growth accident)