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level: Observation of crystal shapes

Questions and Answers List

level questions: Observation of crystal shapes

Question	Answer
What is the name of the outer or surface layer of a crystal structure?	Crystal Face
What is the name of the form, or combination of forms, commonly exhibited by a specific crystal?	Crystal Habit
What is the name for this type of surface mark often seen on beryl?	Etch Pit
What type of surface markings are often seen along the length of rough tourmaline crystals?	Striations
What is this type of surface marking often seen on corundum crystals?	Growth Marks
Which term refers to a crystal structure that exhibits an abrupt change in lattice direction?	Twinning
What feature is seen here in this chrysoberyl crystal?	Three-Way Twinning
What is the term used to describe repeated layers seen as striations across the surface of rough crystals?	Lamellar Twinning
What is the term used to describe a rough crystal that has grown with a repeated, spiky growth of crystals?	Dendritic
Which term describes the refection of the inner structure of crystals that can be seen on the surface, that may help to determine the gem material?	Crystal Form
What is the name of the surface markings seen in this picture?	Lamellar Twining
What is the term used to describe the directional properties of a crystal's structure?	Cleavage
What are the features seen here?	pinacoid
What are the two most common forms seen in rough diamond crystals?	Octahedron
What is the name of these surface markings commonly seen on the faces of rough diamond crystals?	Trigons
What is the name of this surface feature as seen on a rough diamond crystal, that indicates a directional change in a twinned crystal structure?	Re-entrant angle
What type of directional surface feature is shown here on this feldspar crystal?	Cleavage
What is the name for this crystal habit commonly seen in Zircon and Quartz?	Bipyramid