Context: Selenizza is a naturally occurring solid hydrocarbon bitumen found in the native asphalt deposit of Selenice, in Albania, the only European asphalt mine still in use. The rock asphalt is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring & ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

Question: To what location is Selenizza bitumen native?
Answer: Selenice, in Albania

Question: What is it about the mine that is unusual?
Answer: still in use

Question: In what way is Selenizza bitumen geologically different than bitumen found in sands? 
Answer: rock asphalt

Question: What is the variance in bitumen content rock asphalt?
Answer: 83% to 92%

Question: How is the rock asphalt mainly found?
Answer: veins

Question: The soluble matter consists mainly of silica ore and ranges from what percentage?
Answer: Unanswerable

Question: What type of matter ranges from 7% to 20%?
Answer: Unanswerable

Question: The veins are found in the form of what?
Answer: Unanswerable

Question: What content varies from 80% to 93%?
Answer: Unanswerable