The notebooks were not published in Leonardo's lifetime. After he died, they were divided between different people who had known him. They are nearly all in museums or libraries such as Windsor Castle, the Louvre, and the British Library. The Biblioteca Ambrosiana (a library) in Milan has the twelve-volume "Codex Atlanticus".
Some of the things that Leonardo studied are:
Many of the drawings and notes in Leonardo's notebooks are designs, plans and inventions.
Some of the things that Leonardo designed are:
1844
1902
1902 (MCMII) was a common year starting on Wednesday in the Gregorian calendar.
1895
1796
1879
1769
1807
1885
1837
Platinum
Platinum is a soft, heavy, white metal. It is a precious metal. It usually costs more than gold.
In chemistry, platinum is element number 78, and its atoms have an atomic weight of 195 a.m.u.. The symbol for platinum is Pt, from Spanish "platina" meaning "little silver".
Platinum is very malleable and ductile, which means it can be hammered into thin sheets and it can be pulled into wire. Platinum is very stable. Acids do not affect platinum.
The most common use of Platinum is in a vehicle's catalytic converter.
List of rock types
Sorted by name; initial letter means Igneous, Sedimentary or Metamorphic rocks.
List of minerals
This is a list of minerals.
Mineral
Minerals are substances that are formed naturally in the Earth. Rocks are made of minerals.
Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes.
The study of minerals is called mineralogy.
A mineral can be made of single chemical element or more usually a compound. There are over 4,000 types of known minerals. Two common minerals are quartz and feldspar.
A mineral is a substance that usually
One recent definition is:
Alternatively, a mineral is one listed as such by the International Mineralogical Association.
Minerals are different from rocks. A mineral is a chemical compound with a given composition and a defined crystal structure. A rock is a mixture of one or several minerals, in varying proportions.
A rock has only two of the characteristics minerals have–it is a solid and it forms naturally. A rock usually contains two or more types of minerals. Two samples of the same type of rock may have different kinds of minerals in them. Minerals are always made up of the same materials in nearly the same proportions. A ruby is a mineral. Therefore, a ruby found in India has similar makeup as a ruby found in Australia.
Minerals are formed by natural processes. A few substances with the same chemical composition as minerals can be produced by living creatures as part of their shells or bones. The shells of molluscs are composed of either calcite or aragonite, or both.
Traditionally, chemicals produced by living things are not considered minerals. However, it is difficult to see why an organic substance should not be called a mineral if its chemical nature "and" its crystalline structure is identical with its inorganic twin. This issue is now under debate: see Railsback part II.
Minerals form in many ways. The mineral halite, which is used as table salt, forms when water evaporates in a hot, shallow part of the ocean, leaving behind the salt it contained. Many types of minerals are made when molten rock, or magma cools and turns into a solid. Talc, a mineral that can be used to make baby powder, forms deep in Earth as high pressure and temperature causes changes in solid rock.
The extraordinary thing is, that most minerals owe their formation to life, or at least to the Great Oxygenation Event. "Sturdy minerals rather than fragile organic remains may provide the most robust and lasting signs of biology".
A mineral is a solid—that is, it has a definite volume and a rough shape. Volume refers to the amount of space an object takes up. For example, a golf ball has a smaller volume than a baseball, and a baseball has a smaller volume than a basketball.
A substance that is a liquid or a gas is not a mineral. However, in some cases its solid form is a mineral. For instance, liquid water is not a mineral, but ice is.
These properties are used most often:
The particles of ice that make up frost have smooth, flat surfaces. These flat surfaces form because of the arrangement of atoms in the ice, which is a mineral. Such an internal arrangement is a characteristic of minerals. It is the structure of a crystal, a solid in which the atoms are arranged in an orderly, repeating three-dimensional pattern.
Each mineral has its own type of crystal structure. In some cases, two minerals have the same chemical composition but different crystal structures. For example, both diamond and graphite consist of just one element—carbon. But the arrangements of the carbon atoms in these two minerals are not the same, so they have different crystal structures and very different properties. Diamonds are extremely hard and have a brilliant sparkle. Graphite is soft, gray, and dull.
In nature, a perfect crystal is rare. Most crystals have imperfect shapes because their growth was limited by other crystals forming next to them.
Each mineral has a definite chemical makeup: it consists of a specific combination of atoms of certain elements. An element is a substance that contains only one type of atom.
Scientists can classify minerals into groups on the basis of their chemical makeup. Though there are thousands of different minerals, only about 30 are common in Earth's crust. These 30 minerals make up most rocks in the crust. For that reason, they are called rock-forming minerals.
There are many other mineral groups.
People use minerals for many everyday purposes. Every time people turn on a microwave oven or a TV, minerals are being used. The copper in the wires that carry electricity to the machine is made from a mineral. Table salt or halite, is another mineral that people use in their everyday life.
Craft
Craft or handicraft is about making things with one's own hands and skills. The different types of crafts can be put in groups according to the material being used. In the Middle Ages the most common materials were metal, wood or clay.
A craftsman is a person who has the knowledge and skills of a craft. When they have a lot of experience they may be called a "master craftsman". If they are young people learning a craft they are called an "apprentice".
Kim Jong-il
Kim Jong-il, birth name Yuri Irsenovich Kim (according to the Soviet Union's records) (, 16 February 1941 – 17 December 2011) was the Supreme Leader of Democratic People's Republic of Korea (North Korea) from the time of his father's death in 1994 until his own death in 2011. He was the son of Kim Il-Sŏng. Official North Korean propaganda said that Jong-il was born on Mount Paektu (a holy mountain in Korea); but most historians think that he was born near Chabarowsk in the Soviet Union. The North Korean laws made him permanent ruler of North Korea for life. He was sometimes referred to as the "Dear Leader", but this was not an official title. His official title was "Chairman of the National Defense Commission of North Korea", "Supreme Commander of the Korean People's Army" and "General Secretary of the Workers' Party of Korea". Many people in North Korea were imprisoned or killed for speaking out against the Kim regime. Almost everyone in North Korea wore a small pin with a picture of Kim Jŏng-Il or Kim Il-Sŏng on it.
The North Korean government told people of his death through the state media on 19 December 2011. It was said that he had died two days earlier of "physical and mental over-work".
Jong-il was born Yuri Irsenovich Kim on 16 February 1941.