supercomputers
There have been mechanical computers in the past, but they were rare. Today the odds are good that any computer you encounter is digital.
Here are a few examples of the influence of how the cost of materials or manufacturing methods influence the technology those materials and methods are used to create: Rare-earth metals. The rare earths market is important mainly for the production of high strength permanent magnets. These metals are difficult and expensive to separate and work with, and the mining techniques used to obtain them are quite hazardous to the environment. High-precision machining. It takes very expensive dedicated machines to make high-precision machine components such as turbine engine parts. Here like with rare earths, the alloying of metals that make up turbine parts also incur additional cost - more because of the smelting, purification and tempering processes that go into producing the alloys, than the rarity or cost of the alloying elements in this case. Both of these examples involve energy expenditures. Quality has a cost.
A disadvantage of fifth generation computers is that they can give more power to companies to watch what you are doing and even allow them to infect your computer. Another disadvantage is that they tend to be sophisticated and complex tools.
Viruses, which are malicious programs, are the biggest computer hazard. Since computers continue to be a rapidly advancing technology, obsolescence is also a hazard. Since computers are electronic devices, there is some electrical hazard as well, although it is rare. If you spill your soup onto a computer, you can expect a short circuit. There are also many specialized hazards associated with the use of computers, such as the various types of frauds that people perpetrate over the internet.
Computers and electronic devices contain a lot of different materials. Some take a long time to degrade naturally (such as metals), others take a very long time to degrade (such as plastics). Most problematic, however, are rare earth metals and heavy metals such as lithium, traces of mercury and similar substances, which can be poisonous when leaking into soil and ground water.
they are this way because of the same puposes they have and their goal
It is relativley rare to observe a solar eclipse because the sun's light is blocked by the moon
because they are rare
Because they are very rare and endangered
Relatively rare, and rather expensive.
Because they are rare in nature. Black pearls especially
No, diamond is relatively rare.
Rare earth elements are called so because they are not commonly found in high concentrations in the Earth's crust, making them relatively scarce compared to other elements.
Most pedigreed kittens sell for around $700. The Havana Brown, being a relatively rare and exotic breed, commands a price premium. My Russian Blue cost me $700 My Havana Brown cost me $900
About 28 dollars :l, that's a shame because their so rare.
because gold is so rare and hard to find as to where tin is sc easy ti find,and its so rare.
because it requires the Earth the Sun and the Moon to all line up just right and at the same time and that is a rare thing