Thulium Element Number 69 Tm 

 Thulium is becoming difficult to get as a sample for reasonable prices. This very small 9 gram piece has a cast surface, a break and a shiny shear. that shows off the metals beauty.

Tm  69  Lanthanide AW:168.9342  D:8.56  MP:2813  BP:3542 

Thulium's rarity as a lanthanide is second only to Promethium. Thulium is a soft ductile metal, with a kinda greenish hue. Thulium, like most rare earth metals is found in monazite, and extracted using ion exchange methods.

Thulium is extremely rare and expensive, and therefore has few applications. Lasers using Thulium and also superconductors. Thulium can be used as an x ray source for portable x ray devices. some x ray machines use x ray vacuum tubes,  but these machines use and actual radioactive source.  

The first isolation of pure Thulium in 1911 required a procedure of 15000 recrystallizations of Thulium Bromate. Thulium is difficult to process and rare, making it somewhat expensive to obtain a large sample.

Another Thulium lump  about 12.5 grams. 

Ytterbium Element Number 70 Yb 

 Ytterbium is one of the lanthanides discovered in Ytterby, Sweden. This element occurs mainly in monazite, gadolinite and xenotime. Like many rare earth metals Ytterbium has a few exotic uses. I was fortunate to find a nice large crystal chunk at a reasonable price.Fine Ytterbium dust can catch fire or even explode. As with many rare earth metals its not a very good idea to try to melt Ytterbium unless in a vacuum furnace, as it ignite and burn similar to Magnesium

Ytterbium can be used as a dopant for optics and lasers.Ytterbium can be used as dopant material in stainless steel products, to improve certain traits.

Yb169 is a gamma photon emitter and can be used to take x ray photos. Potable x ray machines with no power sources use source materials to take photos. There is 3 allotropes of Ytterbium, and beta is the occurring allotrope at room temperatures.

Ytterbium has one interesting trait, it has the smallest liquid range of any metal

This crystalline Ytterbium chunk weighs 22 grams, and is very fragile. This photo does not capture the beauty of this piece, it is truly stunning 

Yb  70  Lanthanide  AW:173.054  D:6.90  MP:1515  BP:2185