Ytterby lies on the east part of Resarö in the municipality of Vaxholm, Stockholm county. Here, there is a mine that was active from the 1600s to the 1930s. The bedrock in which the mine lies is comprised of pegmatite.
In the1600s, Ytterby was mined for quartz. The quartz was transported by horse and wagon to the iron mills of northern Uppland and was used in iron production in Bergslagen. In the 1700s, quartz was also used at Stockholm's glassworks.
Around 1790, they began to break feldspar from Ytterby mine. Feldspar was used by porcelain factories for the production of English stoneware. The company Rörstrand acquired Ytterby mine around the year 1790.
In 1789, the artillery officer and amateur geologist, Carl Axel Arrhenius, was in Ytterby quarry. He found a strange black stone amongst all the white and light red ones. The stone was very heavy and resembled nothing he had seen before. He sent parts of the stone to different scientists to find out what it was.
Johan Gadolin, professor of chemistry at Åbo Akademi University, did a chemical analysis of the discovery. He concluded that up to 38% of the heavy, black stone from Ytterby was comprised of a previously unknown type of soil. The mineral was later given the name gadolinite. It is slightly radioactive. Further analysis was done and several previously unknown elements were discovered in the mineral from Ytterby. Four of them were named after the place of discovery, Ytterby: yttrium, terbium, erbium and ytterbium.
Ytterby mine was closed for good in 1933. The reason was the deposit's difficult access, and the expensive breaking price due to the mine's depth.
Ytterby mine is a natural monument, which means you may not take stones from there. The rock is radioactive.
The following elements were discovered in the gadolinite which was found in Ytterby quarry:
Tantal (Ta nr 73), Yttrium (Y nr 39), Terbium (Tb nr 65), Erbium (Er nr 68),Ytterbium (Yb nr 70), Holmium (Ho nr 67) and Thulium (Tm nr 69).