What does twinning mean in geology?
Twinning, in crystallography, regular intergrowth of two or more crystal grains so that each grain is a reflected image of its neighbour or is rotated with respect to it. Other grains added to the twin form crystals that often appear symmetrically joined, sometimes in a starlike or crosslike shape.
What causes twinning in crystals?
Transformation Twins – Transformation twinning occurs when a preexisting crystal undergoes a transformation due to a change in pressure or temperature. This commonly occurs in minerals that have different crystal structures and different symmetry at different temperatures or pressures.
Is twinning a crystal defect?
These planar defects can have a profound effect on the way atoms are stacked, and can produce distinct regions called domains within a single crystal. The result is called a twinned crystal. Figure 23 Example of crystal twinning, in which a twin plane separates two regions of a single crystal that are mirror images.
What is twinning plane for rhombohedral crystal?
For a centrosymmetrical crystal structure, both twin laws give rise to the same twin. ). Important examples are cubic twins with  as twofold twin axis or (111) as twin plane and rhombohedral twins with  as twin axes or (001) as twin plane (hexagonal description).
What does twinning mean?
1 : the act of producing or giving birth to twins Rates of fraternal twinning vary from population to population, and the tendency to produce fraternal twins is genetically transmitted through the mother’s line.
What does twinning is winning mean?
“Twinning” is a new portmanteau (かばん語) of the words “Twin” and “Winning”. It means when two people have the same brilliant (目覚しい) thought or action at the same time.
What does twinning mean on Instagram?
“Twinning”—braiding your tresses to match other hairstyles around the world, then simultaneously posting pictures of both artfully knotted heads to Instagram—is an Internet sport dominated by moms and tweens.
What does twinned up mean?
1. born two at one birth. 2. closely or intimately associated, joined, or united; coupled; paired.
What are the benefits of town twinning?
The benefits of town twinning By bringing people together from all over the world, it gives us an opportunity to share problems and solutions, exchange opinions, learn from each other, and create friendships through common interests and issues.
What does it mean when two people wear the same clothes?
3 Answers. Twinsies! (interj., millennial slang) – This is a word millennials say when they are wearing the same piece of clothing, jewelry, etc. When two people are wearing the same clothes, they can say, “We are twinning!”.