Database Of Asteroids
Asteroids are rocky, irregular-shaped objects that have been discovered orbiting the Sun and theorized to be found orbiting other stars.
Asteroid Belt and NEOs:
The majority of known and catalogued asteroids found are within the asteroid belt, between Mars and Jupiter. Our own star has approximately between 1,100,000 and 1,900,000 asteroids larger than 3,281 feet (1km) in diameter, and millions of smaller ones. Of these, there are over 19,000 near-Earth asteroids (NEOs) and some of these, crossing the Earth's orbit, are considered potentially hazardous. Scientist Stephen Hawking stated in his final book that asteroids are the single biggest risk to humanity.
The Kuiper Belt (30 AU to 50 AU from the sun) is a region beyond the orbit of Neptune that contains a large number of small bodies of "celestial debris", remnants left over from the creation of the solar system. The Kuiper Belt, may contain 20 to 200 times the mass of objects as the Asteroid Belt. Over 3000 of these "Trans-Neptunian Objects" have been actually categorized, and it has been postulated that there are as many as 100,000 objects larger than 100 km in diameter. Given their extreme distance from Earth, the composition of these KBO's is difficult to determine. However spectrographic studies have indicated composition similar to comets - water ice, light hydrocarbons and simple nitrogen compounds including for example methane, ethane, carbon monoxide, hydrogen cyanide, and ammonia. These are valuable materials in space, especially water ice.
The Oort Cloud (2,000 AU to 200,000 AU from the sun) is a fascinating region that has been proposed to contain a huge number of "icy planetesimals". These are too distant to be observed directly with current telescopes but may be detectable by observing dips in the light output of stars as the objects passes in front of the star. Interestingly, the Oort cloud extends as far as the sun's "Hill sphere" or region of gravitational influence. At these enormous distances, the sun's gravitational pull is weak and beyond 200,000 AU, objects are more significantly influenced by other stars and even the "galactic tide" exerted by the Milky Way itself. It is theorized that objects from within this cloud are occasionally dislodged from their orbits and sent toward the inner Solar System - resulting in the phenomenon of long-period comets such as Halley's Comet. The outer Oort Cloud has been theorized to contain trillions of objects greater than 1km in diameter - though these may be tens of millions of kilometres apart due to the extremely large size of the cloud. it has been estimated that the cloud may have a mass of objects five times that of the Earth. Most of these are regarded as comet "dirty snowball" type, while it is thought that 1 to 2% may have rocky / mineral composition similar of the asteroid type.
Asteroids are potentially a very significant source of valuable raw materials. A number of private companies are commencing plans for commercial asteroid mining, which has been predicted as the industry that will make the world's first trillionaire! The potential mineral value of asteroids is truly astonishing. According to Asterank, there are over 500 asteroids each worth over 100 trillion. To put that into perspective, the world's current annual GDP (2018) is around 84.7 trillion. Note of course that there would need to be uses found for all these minerals. You cannot suddenly dump 100 trillion worth of rare earth elements onto the London Metals Exchange without crashing the market.
At a certain point however, harnessing this resource will become technologically feasible - and perhaps enormously more profitable than mining on Earth, which leads us towards a potential scenario where the Earth can be restored, instead of destructive mining. It makes sense for heavy industry to be in space, for several reasons.
For both reasons above - the positive potential asteroids hold for enormous wealth, and the negative potential they have to end our civilization, it should be considered absolutely vital to study asteroids, in particular to map their locations and trajectories, and to develop reliable methods of capturing them and / or manipulating their orbits.
Further Reading / Research
Density of Asteroids
Asteroid Density, Porosity, and Structure
Asteroid Masses and Densities
Asteroids: Sources of Precious Metals
Asteroid Mining: Key to the Space Economy
Asteroid Retrieval Feasibility Study Volatile Products from Carbonaceous Asteroids
The Role of Near-Earth Asteroids in Long-Term Platinum Supply
Near-Earth Asteroid Mining
Review of Asteroid Compositions
The Reflectance Spectrum of Troilite and the T-Type Asteroids
A database of chondrite analyses
Asteroid Mining - Alglobus.net
Mining the Sky
The London Metal Exchange
Lance Benner's delta-v calculations
NASA LVDC Fact Sheet
JPL Close Approaches
Minor Planet Center
Asteroid Lists And Databases
http://www.asterank.com/ - has a database of over 600,000 asteroids together with their mass and estimated mining value!
JPL's Small Body Database
MIT SMASS Survey
Classified List of Meteorites https://en.wikipedia.org/wiki/Category:Lists_of_asteroids