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Atomic # 

3

Li

Species =

115

Lithium

In general terms, we might think of lithium as a thearapeutic.  As an element, we finally get to the first solid, at least during ambient conditions on earth.  Located in the second row at the extreme left side of the periodic table, we find lithium beneath hydrogen.  Sorry, but if you like Star Trek, I still can’t find dilithium. Back to our element: lithium is rare in the universe but on earth is the 27th most common element.  You might compare that to the first two elements – this group of three make up the sum total products of the Big Bang.  

 

Minerals containing lithium are common and collectible.  Believe it or not, they are coveted by some collectors. Most of the minerals are likely to be found in lithium-rich pegmatites.  Spodumene, which includes the varieties kunzite, triphane and hiddenite, is another silicate mineral with a formula of LiAlSi2O6.  It is a silicate; further we find that it is a representative for the subclass of inosilicates.  The rarity of lithium is an issue when you compare it to the rest of the main components in spodumene.  They are all part of the Big Eight.  About 8% by weight of a typical spodumene is composed of lithium oxide.  Collectors have a special interest in the pink to purple color we find in crystals that are sold as kunzite. You will find out that it is a common practice among vendors to use varietal names with or without the proper species names.  Rickwood, 1981, describes a giant spodumene where the length is 12.80 m and the weight is 379,480 kg; it is from South Dakota. 

 

Petalite, a lot less common than spodumene, is far less sought after by collectors.  It can be on the pricey side and lacks much color in many examples.  The formula is similar to spodumene – LiAlSi4O10. It is also a silicate.  We note crystals are not easily found – another negative factor for many mineral collectors.  After all, we really want crystals!

 

Montebrasite and a relatively similar species, amblygonite, are a pair of phosphates that contain lithium.  So, here we have the elements phosphorus and lithium, both lying outside the Big Eight.  The difference between the two species is based on whether your sample contains OH (montebrasite) or F, which will be amblygonite.  This is not easily determined.  Both species are mainly composed of the same elements:  lithium, aluminum and the phosphate radical.  Crystals are available, medium-priced and of some interest to collectors.  

 

Finally, lepidolite, a lithium mica, is probably thought to be more common than it really is based on recent study.  Further, a review of the name shows us that it is not a currently valid species.  In spite of all these conditions, it is often found in collections and vendors may offer the samples labeled lepidolite.  Crystals are easily acquired and generally inexpensive.  Colors can vary but pink and purple samples seem to be the most desirable to collectors.  Back, 2018 indicates two species that are probably the correct names for most of the specimens we used to call lepidolite.  Those two species are trilithionite and polylithionite.

 

For lithium production, all of these minerals contain a few per cent of lithium, average values are around 10% lithium oxide.  We also note some production occurs from brines.  The lithium composes about 45% of the oxide so we would need a lot of raw material to get much lithium.  Massive quantities do occur occasionally so the supply is not a critical problem.  Other species you may see used for a source and even collected by scientists include cryolithionite, eucryptite, cookeite, zinnwaldite, manandoite, triphylite, lithiophilite, fremontite, and sicklerite.  Some of these are not currently classified as valid species according to Back, 2018.

 

An example analysis of lepidolite is representative for the element lithium.  

K2O 10.02 FeO 0.04

Li2O 3.70 MnO 0.92 See Handbook for ideal and empirical 

Al2O3 28.83 CaO trace formulas. 

SiO2 48.58 Na2O 0.87

F 4.93 Rb2O 0.91

H2O+ 2.56 Cs2O 0.16

H2O- 0.54

-O= F2 2.08 Total = 100.08

This sample was from the Stewart mine, Pala, California.  [Via Handbook]

Perhaps you already noticed the rather low percentage of lithium oxide in the sample above.  Yet, because lithium is in the ideal formula, I consider it to be a good representative of this element in a mineral.

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