5,000 YEAR OLD ROCK CRYSTAL, SEVILLE, SPAIN

Some say it is a Rock Crystal dagger, others say it is a Rock Crystal spear head. 16 arrow heads and weapons made from Rock Crystal were found in a tomb in Spain with the remains of 25 people. 

https://www.dailymail.co.uk/sciencetech/article-9177867/Rare-5-000-year-old-crystal-dagger-uncovered-Prehistoric-Iberian-megalithic-tomb-Spain.html

In Montelirio Tholos the bodies of 20 Priestesses were found. Archaeologist's believe that the women were poisoned with mercury. Due to the condition of their bones with arthritis and osteoarthritis, it is thought that they either walked a long way or were dancers. 

https://spainsnews.com/the-mystery-of-the-20-priestesses-poisoned-with-mercury-4800-years-ago-in-seville-culture/

 Academia have been unable to ascertain the origins of the crystal. 

https://youtu.be/dRW39e9js9I