2. Content of PowerPoint Introduction What is crystals? Crystals produced by crystallization Procedure of crystallization

3. Introduction of Crystallization Crystal is a solid body. The formation of a crystal is called crystallization. Crystals are grown in many shapes. In order for crystallization to take place a solution must be "super saturated".

4. Crystallization is a technique. It’s a process of formation of solid from solution. This can be done by various methods ……*On the following slides we are going to introduce more about crystallization.

5. A crystal is a solid Fluid substances form crystals when they undergo a process of solidification. Most metals encountered in everyday life are poly crystals. Crystals are often symmetrically intergrown to form crystal twins. Crystal structure will form depends on the chemistry of the fluid The process of forming a crystalline structure is often referred to as crystallization. Crystallography is the scientific study of crystals and crystal formation.

7. Quartz Crystal Crystallography: Hexagonal Chemical Composition: Silicon Dioxide Hardness: 7 Quartz is one of the most abundant minerals in the world. Sand is mostly comprised of quartz; even the dust in the air is high in quartz content. The most well-known form of quartz is clear rock crystal, and it may be found throughout the world. Particularly fine specimens are currently found in Brazil, the United States etc. The largest single quartz crystal recorded was approximately 20 feet long and weighed more than 48 tons.

8. Bismuth Crystal Chemistry: Bi Crystallography: Hexagonal Crystal Growth and Habits: Bismuth often forms crystals in parallel groups or as hoppers. It can also be reticulated, or granular. Color and optical properties: Silver white with a slightly golden hue. It tarnishes to produce an iridescence. Opaque Hardness: 2 - 2.5 Occurance: Native Bismuth is a rare mineral that occurs in hydrothermal deposits associated with cobalt, nickel, silver and tin. It is also found in pegmatites and in topaz bearing tin and tungsten veins. Mineral Name: From the German wismuth, meaning white mass.

9. Insulin Crystals Gallium Crystal

12. When the temperature of the solution is increased, hot water can dissolve more solid substance than cold water. As a saturated solution cools, the water molecules move closer together again and there's less room for the solution to hold onto as much of the dissolved solid.

13. Crystals begin to form and build on one another as the water lets go of the excess solute. This process is called recrystallization and, depending upon conditions, one may obtain a mass of many small crystals or one large crystal.

15. During recrystallization, crystals start growing by a process called "nucleation". Particles of dust on the surface of the solution can initiate crystallization. However, this situation is somewhat uncontrolled.

16. To get controlled growth, a "seed crystal" is tied on a piece of thread and is submerged in the solution. As the temperature of the solution continues to drop, more crystals will accumulate on the thread.

17. The rate at which crystallization occurs will affect crystal quality. The best crystals are the ones that grow SLOWLY.

18. Cut a piece of thread of 20 cm long.

19. Tie the seed crystal on the thread.

20. Tie the thread to the vial cap.

21. Adjust the length of the thread making sure that the crystal does not touch the bottom of the vial and dangles inside the vial.

22. Get the warm saturated solution of the crystal that you want to grow.

23. Pour the saturated solutions into your vial.

24. When the solution has come to near room temperature, or when you see crystals start to form on the bottom of the vial, gently place the seed crystal in the solution.

25. Allow the vial to sit undisturbed.

26. Group Members F.3A Andrea Choi (11) Hannie Choi (12) Jane Chu (13) Claudia Fan (14) Samantha Ip (15)