coffee from seeds of dates I once heard that it is possible to make coffee from seeds of dates.

I heard that you have to bake them in a low temperature.

So, I took seeds of dates, baked them in the oven in 100 degrees celsius for about an hour, and then tried to grind them.

The blades of the grinding machine broke.

Before I try again, I would like your seasoned advice: how can I make coffee from seeds of dates?

How can I know in advance that the seeds are soft enough for grinding?
Handbook of Indices of Food Quality and Authenticity p474:


  The most important coffe substitute is undoubtedly chicory
  ...
  Chicory itself is reportedly adulterated by roasted beetroot
  ...
  Barley, malt, rye have been used...
  Seeds which have been used include chickpeas, peanuts, soybeans, other beans
  ...
  Date seeds contain less extractives than coffee...


All are roasted somehow. 
Coffee: Related Beverages gives some roasting directions, but I don't immediately see a protocol for date seeds.

Roasted Kentucky Coffee Tree seeds are even still used occasionally.

If I wanted to grind date seeds, I'd smash them with a hammer first. Many seeds are unbelievably tough until broken.