Ferruginous Quartz--kinda

*from Valencia, Spain.
*The red quartz crystal is 20 mm tall. 55 x 50 x 35 mm overall.

These crystals have a great history. They are called Jacinto de Compostela which translates into Hyacinth of Compostela. Compostela is a city in Spain. It was named by pilgrims traveling to Santiago who carried these red quartz crystals as a talisman. These red quartz crystals don't occur in Santiago. They were only brought there by the pilgrims. 

The red is not caused by iron as the name ferruginous suggests but by clay and gypsum particles trapped as inclusions. The matrix is gypsum. Great luster!