Dimes and quarters are of equal value...
 

At least by the pound.

The same weight of dimes or quarters has the same value.

100 dimes is the same weight as 40 quarters.

$45 in dimes weighs the same as $45 in quarters.


The more you know...

Buying some 90% silver...?

Huh, cool.

Pre 1964 half dollars as well

Morgan and peace dollars are just a bit heavier per dollar, but im not sure why.

Metal content was money in the past

a $2.50 gold coin weighs half as much as $5, which is half as much as a 10$ (eagle), which weighs half as much as a $20 double eagle.

Much of the worlds historic coins follow this as well

Sure, but in this day, the metal value of our coins has nothing to do with their face value. It's just coincidence that dimes and quarters have the same face value for each physical gram of material.

Nickels and pennies don't follow that.

I also only know this because I was weighing a bunch of coins to see roughly how many I have before I swing by the Coinstar machine.

its not a coincidence, unless you consider keeping the historic coin diameter/thickness a coincidence. The value of silver coinage used to be based on weight. They stayed the same physical size over many coin design generations and are made from the same (density) materials. Its a direct result of them being silver coinage in the past.

Nickles and copper coins were never silver coinage and don't have this history. there used to be half dimes and 3 cent silver pieces that followed this as well.

I wonder what an ounce of Bitcoin is worth.

Less than it was a few weeks ago

That makes sense!