Hermóðsdögg or Hermóðardögg (kvikasilfur)

Mercury is the only metal for which the alchemical planetary name became the common name. The god Mercury was the quick messenger of the gods, hence the synonym "quicksilver". The Nordic equivalent is Hermóður, the messengergod nick-named "hinn hvati" (the speedy one).  Because mercury looks like dewdrops, I decided to call the element "Hermóðsdögg".

Ormsilfri (Platinum), Ormsilfringar (platinum-group elements)

Fáfnir was a dwarf in Old Norse mythology who was cursed by gold.  The construction "Ormsilfur" (the serpent's silver) doesn't make sense at first glance, but can be used for platinum, which has its name from it silvery appearance (Spanish: plata (silver) + "-ina" (dimninutive suffix) , platina, the little silver). In Icelandi "hvítagull" (white gold) has been used, because the element is situated next to gold and looks like silver, so "ormsilfur" works for "platinum"!

For the Platinum group of elements: Ru, Rh, Pd, Os, Ir, Pt the term Ormsilfringar can be used.

Elfarylfri (rhenium)

The construction "ylfri" for W (tungsten, wolfram) is a combination of "ylfi", a neuter noun derived from "úlfur" (a translation of the first part of "Wolfram") with addition of the first "r" in the second member "-ram", which makes the word sound like the dative of "silfur", silfri.  "Ylfi" on its own doesn't sound like the name of a metallic element. Addition of the "r" in "ram" does: ylfri

Rhenium was named after the river Rhine and is positioned right next to tungsten (wolfram): Elfar-ylfri, a funny rhyme word.  I like it.

So we have three words for rhenium

1) torsuðumálmur (highest boiling point)

2) elfarylfri (the "wolfram" (tungsten) named after a river (Rhine))

3) eðalþungsteinn (noble tungsten. Rhenium is a noble metal)

Fjandlyfti (Flúr)

 The most corrosive gaseous element is the halogen fluorine. Fjandlyfti

Germanium: saxefni, hálftin, ofurkísli and blendismelmingur

 Germanium:

So there are four possible names for germanium:

1) saxefni (the element was found in "Saxland" (Saxony) in Germany, so instead of naming it after the whole country, Germany , we can name it after the specific provinc, saxony: SAXONIUM (saxefni)

2) blendismelmingur: Germanium is commercially extracted from the zinc ore "sphalerite"  or "zinc blende"(ZnS). Just like the term "salt" originally designated only NaCl before it's meaning was broadened to designate "substances produced by the reaction of an acid with a base", "blendi" on itself was used for "Sphalerite". In Icelandic "sinkblendi" is used, but one can use "blendi" in Icelandic in the original narrower meaning. The fpur metallic elements, commercially extracted from sphalerite are: gallium (blendisál, closest to aluminium), cadmium (blendissilfur, closest to "silver"), indium (blendistin, closest to "tin") and germanium (blendismelmingur, the only "metalloid" (orðabanki: "málmbróðir", "málmungur", "mélmingur") extracted form "sphalerite"). So "blendismelminger" (I chose a compound with "melmingur" because of the vocal harmony) means "the metalloid in sphalerite".

ofurkísli (eka-silicon, the kind of terminology used by Medelejev before the element was discovered, the heavier brother of silicon)

hálftin (lying between silicon and tin, constructed after the word: hálfþrítugur, which doesn't mean 20 but 35)

Beryllium (esmi, from "Esmeralda" (smaragður))

Beryllium (esmi)

Beryllium is a exceedlingly diffeicult element to name in pure Icelandic. There's really only one word that is linked to the element and that's the loan-word "smaragður", "emerald", a greenish variety of beryl in which the element was discovered by Nichola-Louis Vauquelin in 1798. It exists in other languages as a feminine personal name: "Esmeralda" and the shorter form "Esme".  I have no idea how well-known this portuguese name is in Icelandic.  There is one person in Icelandic that has this name.  

I decided to borrow this name for Portuguese in a way that it sounds genuine Icelandic: the neuter noun "esmi", which I choose because of it's sounding similar to "efni" and the i-shifted names of elements like "vetni" ("hydrogen", from "vatn" (water), "ildi" ("oxygen", from "eldur" (fire)), "lyfti" ("nitrogen", from "loft" (air), and my own construction : "kelki" ("calcium", from "kalk" (lime)), "telki" (magnesium, from "talk" (talk)", "selti" (chlorine, from "salt"), blyfti (radon, a fusion of "blý" (lead) + "-lyfti" (loft), "blýþungt loft").

So "esmi" is in my opinion the best option.

þungsilfri (-s) (platinum)

 Apart from "gylfri" and "hvíyagull", there's another possibility for platinum: þungsilfri. It would be absurd to call the heavier chemical brother of silver, gold, "heavy silver", because in this case it would be inappropriate to call a yellow metal "a kind of silver". Add to this the fact that the Spanish called the element after "silver" (little silver, plata + -ina) and constructions like "þungsilfri" might be a good alternative for "hvítagull" (white gold).