It's only a matter of time before someone puts coins into a time machine. How will you know if your coins are real coins or fakes? This instructable contains helpful tips on collecting coins from the future.

Step 1: Measure Radioactivity

Step 2: Analyze Crystal Structure

Step 3: Analyze Elements

Step 4: Examine Texture

Step 5: Check for New Manufacturing Techniques

Step 1: Measure Radioactivity

Coins from the future may have been exposed to high levels of radioactivity, either from nuclear fallout, proliferation of nuclear breeder waste, or from the time travel itself. Either way, it is important to measure the radioactivity in order to know how to properly store the coins.

A Gieger Counter is a relatively inexpensive way to measure radioactivity. Any coin with higher radioactivity than the background level may be a coin from the future. [The logic is undebatable: since radioactivity decays over time, an older coin would have less radioactivity than a newer one.]

Step 2: Analyze Crystal Structure

It is likely that advanced fabrication techniques will be developed. These techiques may create new or rarely seen crystal structures. Such techniques include laser sintering.

An X-Ray Spectrometer, shown here, will non-destructively measure the crystal structure and compare it to known crystal structures.

Step 3: Analyze Elements

If you still have not determined whether the coin is from the future, it may be time to make a destructive test to determine the composition of the coin. Due to declining oil reserves in the future, it is unlikely that coins will be made from plastics (an oil derivative), and more likely that they will be metallic or ceramic.

A Mass Spectrometer vaporizes a small sample of the coin and measures the atomic weight of the elements released.

Step 4: Examine Texture

Maybe new materials may too expensive for a future economy. Coins from the future may use texture, as shown in this photo. The photo also appears blurry -- this may be a result of high levels of radioactivity.

Step 5: Check for New Manufacturing Techniques

Coins of the future may be made with interesting new features -- like the metal inset shown in this photo. Use of two dis-similar metals may also allow this coin to power future extremely low-power pay devices.

I hope this helps everyone who intends to collect coins from the future.