Icelandic equivalent for "Devon":

"Devon" is derived from the toponym "Dumnonia", the region near Cornwalls, inhabited by the Dumnonii, which is thought to mean "deep valley dwellers" from proto Celtic *dubnos 'deep'. In the Brittonic, Devon is known as Welsh: Dyfnaint, Breton: Devnent and Cornish: Dewnens, each meaning "deep valleys." (source: English Wikipedia: Devon). "Dubnos" also means "dark" and is the root of the Nordicized Celtic name "Dufþakur". There's also the name Dufn(i)all, which is the Viking corruption of the original form of Donald, in which "Dufn", comes from Domn (world)

I would take "Dufn" as the root for derivations of the topnym "Devon"

Devon, Devonshire: Dufnskíri ("Skíri" old Icelandic borrowing from Anglo-Saxon, the equivalent of "shire")

Devonians (the cEltic tribe of the Dumnonii): Dufnungar , dufnverjar

Devonian (in geology): "Dufneska tímabilið", "Dufnöld", but combinations with "velskur" are aso possible. The Celtic people were called "welsh" (strangers) by the Anglo-Saxon invaders: "Dufnvelska tímabilið". The name is often called "the Age of Fish", because fish reached a large diversity during this era and the first ray-finned and lobe-finned bony fish appeared, so "frumfiskatímabilið" or "Fiskafrumöld" is also an option.

Devon (a feminine personal name): Dufný (Dufný, Dufný, Dubnýjar)

acetylation - eðkun (from edik)

new words

Avogadro's number (chemistry): afgaðresk tala
Giotto (space probe): Djotti, Djottakanni
jujube (fruit): brjóstaldin (Dutch: borstbes (literally translated: brjóstber))
The Spirit of St Louis (Charles Lindbergh's plane): Sanktalúðvíski andinn

smyrlingsþumlar (mummy-thumbs, date-fruit)

The word date originates from the Latin dactylifera, which means "finger-bearing".  But dates don't actually look like fingers, they look like a special kind of fingers, they are "thumb-shaped'.  And they look brown and wrinkly, like the thumbs of a mummy.  The term "mummy-thumbs" actually pack a remarkable lot of information about how dates look like: The first element smyr(ð)lingur, "mummy" refers to Egypt, which is situated in that part of the world where dates are cultivated, while it describes the brown colour and wrinkly surface of the fruit, while þumlar, "thumbs" is descriptively more precise a reference to the etymology of the word "date".

pyrite (glópagull, brennisteinskís)

The term pyrite in its original meaning, before its meaning was extended to a large class of minerals, designated iron sulphide, which has a golden colour and was often mistaken for gold, hence the name fool's gold, of which the Icelandic glópagull is a literal translation.  But there are many more possibilities to form Icelandic names for this mineral:

hræsnistár freyju (the tears of the godess Freyja became gold, so her crocodile-tears must have turned to "fool's gold".)
hégrátssteinn (hé (false, as in hégómi, hégilja) + grátur)
vanynjublendi (= blende of the Waness).  In old mineralogical terminology, "blende" was originally used for Zinc sulhide, but also more generally to denote minerals that are deceiving, mostly metal sulphides, that didn't yield the right metal.  See: http://de.wikipedia.org/wiki/Blende_(Mineralogie)
Pyrite has all the properties mentioned it the German wikipedia article to be regarded as a blende: sulphide, metal-like, yellow or black, deceiving. 
brennigull (brimgold): Pyrite was named after fire, it is a compound with "brennisteinn" and was used as a raw material to produce sulphuric acid (brennisteinssýra)
Pyrite is the most common of the sulfide minerals. The name pyrite is derived from the Greek πυρίτης (puritēs), "of fire" or "in fire", in turn from πύρ (pur), "fire". In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel.  (see http://en.wikipedia.org/wiki/Pyrite )

Surtarjárn: Iron of Surtr (constructed like Surtarbrandur)

þolkíslungur (topaz)

There is no Icelandic term for "silicate" or "silicate mineral", although it is relatively easy to construct one.  The Orðaskrá um eðlisfræði og skyldar greinar mentions kísl for silica (SiO2, silicon dioxide).  Silicates are compounds with silica or oxidized silicon, so all we have to do is adding -ungur or
-ingur to kísl: kíslungur.  compounds: e.g. neosilicate = nýkíslungur.  The topaz is the hardest silicate mineral in nature.  Initially I thought of kóngakíslungur, harðkíslungur, but the best choice in my opinion is þolkíslungur.

Erkihúrra! - Erkúrra - Eureka! Archhurrah!

The famous interjection Eureka, used to celebrate a discovery and attributed to Archimedes literally means "I have found it" and is the 1st person singular perfect indicative active of the verb heuriskō "I find".  Because the same sequence of the consonants (RK) are found in both EUREKA and the first part of Archimedes' name 'Archi-' derived from 'archos' (master, the first) and identical to the English arch- in archbishop, and Icelandic erki- in  erkihertogi, it is possible create an original, eccentric variant to the greek exclamation: erkihúrra! or the contracted form "erkúrra" (also possible in English: archhurray!), which sound as a weird pronounciantion of the Greek word without being unacceptably unsimilar in sound.  Erki- functions as an augmentative prefix, while at the same time it can, in this particular compound, be regarded as a reference to Archimedes.  Certainly, the addition of  erki- to an exclamation like húrra! is quite unconventional, but there's no rule that explicitely forbids this. The reason this kind of exclamations haven't been constructed yet is because we have a special case here.  It's because foreign exclamations aren't targeted by conventional neologists, not because the construction is morphologicly inappropriate.  It's a matter of getting used to it. I like the boldness of these kind of constructions, its eccentricity and, above all, its UNinternational character, despite its being constructed with two loan-words.  This result is much purer than the adaptation evreka or a the literal translation "Ég hefi fundið það!", which is too long for an exclamation.

On the Icelandic version of the name Archimedes:
Archimedean: Erkimeðs- (This Greek personal name means 'master of thought' and is derived from the Greek element archos (master) combined with medomai (to think, to be mindful of). The first element is identical with Icelandic prefix erki-, the second medes can be adapted to -með, like in the Arabism Múhameð. The reason this is wasn't done is because there has never been real uniformity in the icelandification of Greek and Latin names. In the Íslenska alfræðiorðabókin, the Greek personal name Euclides and is adjectival derivation Euclidean were entered as Evklíð and Evkliðskur respectively, no -es or -esar here, while Euripides, an other name ending in -es preceded by the consonant 'd', became the semiadapted, halficelandic Evrípídes, instead of Evripíð. The Icelandic Evklíð is similar to the French Euclide and both are examples of good adaptations. So my proposition for the name Archimedes and its derivative Archimedean are Erkimeð and Erkimeðskur/Erkimeskur respectively, instead of the far too unicelandic Arkimedesar- or Arkimedískur.
Erkimeðsstuðull (Archimedean constant, the number Pi)
Erkimeðskuðungur (Archimedean spiral)
Erkimeðsvirðing (Archimedean valuation)
Erkimeðsraðsvið (Archimedean ordered field)