### crystal | ice:

Sea ice
* Most sea ice has surfaces
  - is seasonal, melting and growing annually
* Most sea ice reflects income solar radiation
  - sunlight
* Some sea ice affects food sources.
* affects food sources of polar bears
  - the system at many different levels
* arises as seawater freezes.
* can form a hazard to shipping and to towing scientific equipment.
* complex matrix of physics and biology.
* freezes from sea water and grows to cover large areas of polar oceans during winter.
* includes grease ice, frazil ice, pancake ice and pack ice.
* is also full of cracks, and so it can disintegrate before it melts.
* is an important part of the global climate system
  - integral part of the Arctic Ocean
  - by nature located in remote, inaccessible regions, and the ice extends over a large area
  - colonized internally by many microorganisms
  - formed in polynyas and advected southward across the shelf
* is frozen sea water that floats on the ocean's surface
  - seawater that floats on the surface of the ocean
  - habitat for the algae at the base of the polar food web
  - home to algae that feeds krill larvae, Without the sea ice, krill populations diminish
  - ice that floats in the ocean
  - important to the climate and the ocean in a variety of ways
  - less salty than sea water
  - loose pack ice that is often too unstable to carry research instruments safely
  - maintained in a metastable state through a network of negative feedbacks
  - one of the most sensitive model components to an incorrect initial state
  - part of the Earth's biosphere
* is the habitat of ringed seals which are the predominant prey of polar bears
  - name given to all the ice that freezes from the sea water
  - white, and glacier ice is purple
* lasts all year and never melts completely.
* mushy layer.
* phenomenon that is dynamic on a variety of scales.
* plays an important role in the ecosystem.
  - the sun's rays
* special feature of the Arctic, and most wildlife there depend on it in some way.
* stretches out of sight to the north.
* supresses the energy dynamics between ocean and atmosphere.
* surrounds a large area of the Canadian Atlantic coast during a severe winter.
* tends to float on denser salty water.
+ Arctic ecology, Environment: Ecology
  * Sea ice is ice that floats in the ocean. It is made of frozen seawater. It is important because animals live and sleep on the ice, especially in winter. Sea ice lasts all year and never melts completely. There is less ice during the summer than during the winter.

Slush ice
* has only half the strength of blue ice.
* is about half as strong as clear blue ice, while new ice stronger than old ice
  - half as strong as clear, blue ice

Solid ice
* Most solid ice has compositions.
* is less dense than liquid water
  - melted into liquid water

Thin ice
* Some thin ice is surrounded by walls.
* is more likely early in the winter, and toward spring.

Individual crystal
* are prismatic to acicular and striated vertically.
* can be quite transparent and appear similar to certain gypsum crystals
  - display a wide range of crystal faces
* connect to other crystals and ultimately form larger structures.

Ionic crystal
* Most ionic crystal has properties.
* are extremely stable since considerable energy is required to break ionic bonds
  - hard and have relatively high melting points
  - hard, have high melting points, and are brittle
  - normally transparent to visible light
* owe their colors to crystal-field mechanisms.

Jade
* is green
  - precious stones
* leaves, large and small cabochons in various semi-precious stones.
* symbolizes purity, nobility and beauty.

Large crystal
* are rare and massive forms are more common.
* dissolve more slowly than small crystals.
* have an almost striated or grainy appearance.