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 How it Forms
Because the Eurasian tectonic plate and the Philippine Plate are actively colliding and compressing they underwent two times of metamorphism and it's because of this that Fong Tian jade is formed.
Figure 1. A geologic view of the Hua Lian area over 100 million years ago. Deep sea sediment accumulated over the Pacific Plate where it was subducting under the Eurasian Plate.
Figure 2. The sediment is carried below the Eurasian Plate.
Figure 3. The friction and pressure of subduction caused parts of the plate to break off and mnix together with the ocean sediment.
Figure 4. Between the 2 tectonic plates there is now a mixed area of fractured plate and sediment.
Figure 5. Following subduction, in such a high pressure low-temperature environment the sediment mixture changes its nature.
Figure 6. From 60-70 million years ago, the area near Taiwan was a shallow marine basin in the continental shelf metamorphism where large quantities of sediment accumulated and later formed the Central Mountain Range of Taiwan.
Figure 7. 4-600 million years ago the Philippine Plate and Eurasian Plate collided causing the sediment area and rocky layer to raise out of the ocean near the basin around Taiwan. This later became the East Coast Mountain Range.
Figure 8. Because of the collision of the plates the serpentine and black schist once again metamorphosed. The area now know as Hua Lian raised up from the ocean at this time.
Figure 9. From this series of processes, there was metamorphosis between serpentine and black schist, thus giving rise to the bean-shaped or irregularly-shaped jade mines.
(Source: 2006 Geology published by the Ministry of Economics, Republic of China. Volume 25(4). Article name: Taiwan's Mountains, Rivers, Land and Rock.)
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Discovery