2ndC Roman silver coin - 'cooking' it to remove crust

This is probably a Flavian (Vespasian, Titus or Domitian) but it is a similar reverse with sacrificial implementia.  This one has "TRI POT" (Tribunicia Potestatum or the Tribunician Powers) across the bottom of the reverse, and that's a common reverse type for the Flavians. 

Other emperors used the sacrificial implements as a reverse type. So I can't be certain who it is until there's a bit more obverse detail to go on. I can tell you that they're often associated with issues for the Caesar - the "heir apparent" - (if there is one) so I'd make a guess there's a good chance this may be Titus, but I believe Vespasian used this same reverse.

When you've revealed some obverse details I should be able to tell you better what you've got here.

Mark

1641-3 Charles 1st hammered silver shilling - Triangle in circle mintmark

Tower mint under Charels 1st

1526-32 Henry VIII hammered silver half groat - Cross patonce mintmark

Archbishop Warham - WA by shield

Rev CIVI/TAS/CAN/TOR - Canterbury mint

1stC Roman coin - straight into 'cooker' to clean off crust

What you have here is a denarius of Trajan, 96-117 AD.  It was during Trajan's time that the Roman Empire achieved it greatest overall size - it would never again be so large.  Although Hadrian and others of Trajan's successors were quick to lop-off some of the further flung and less easily administered and defended areas, Trajan's rule ushered-in the era of "The Good Emperors"  The 2nd century, therefore, was noted for a general condition of relative peace and prosperity the likes of which would not be seen again (arguably, even in our own time).

This specific piece has "Genius" (Genio Populi Romani - the genius or motivating spirit of the Roman People) standing left holding a patera - a sacrificial vessel for pouring libations - and a cornucopiae.  The legend on the reverse, as is often the case on Trajan's coins, cites only "The Senate and The People of Rome" and the statement that Trajan was "The Optimum Prince".

The obverse legend (which is somewhat unclear on your specimen, so far) will be the typical 2nd century "laundry list" of titles: IMP TRAIANO AVG GER DAC P M TR P COS V P P.

The catalog references for this piece are: RIC II 181; RSC 395. 107 AD

Mark

1351-2 Edward III hammered silver groat - Cross 1 - Letters C & E open

Obv EDWARD D.G. REX ANGL Z FRANCE D HYB

Rev CIVI/TAS/LON/DON - London mint

1859 Victoria milled silver Florin (24 pence)

1247 Henry III hammered silver voided long cross - Class 5b

Obv HENRICVS REX

Rev WIL/LEM/ONC/ANT Moneyer Willem of Canterbury

First qtr'd 1634 Charles 1st hammered silver shilling (12 pence) I have seen

Obv **ROLVS D G (Carolvs)

1247 Henry III voided long cross hammered silver penny

Very unusuall BC Republican Roman silver coin - straight into the 'cooker' but there is enough detail sol I have sent it off to Mark Lehman for his views before I clean it up

SILVER Denarius - 49 to 44 BC,
by JULIUS CAESAR,
Refers to MILITARY VICTORY of GAUL !! When this denarius was first minted, it was a day's wages for one of Julius Caesar's soldiers.
Obv: Elephant Trampling a Serpent
Rev: Priestly Implements

Obv Elephant

Rev Bird facing left

Mitch Chris posted on the forum a picture and ID of the coin and it appears to match.

that's a Julius Caesar elephant denarius.  The elephant is walking right trampling either a serpent (not too likely, but possible) or a Celtic Carnyx - a war trumpet in the shape of a serpent or dragon - in the generous exergue below, you have CAESAR in large, clear letters no one could mistake.  The reverse is an assortment of priestly implements - the exact order and assortment may vary from issue to issue, but will include various items from this list: simpuulum (ladle), aspergillum (sprinkler - looks like a hand-sized floor-mop) jug, knife, axe, apex (pontifex's special hat) and lituus (curved wand).  Caesar held the post of Pontifex Maximus from an early age, which despite its odd set of restrictions, allowed him entry into the halls of power and was his launching-pad to greatness.

The type dates to 49 BC, or about the time his political career in Rome really hit stride, 5 years or so before his demise.  I believe this was well after his abortive attempts at conquering Britain, although I'm not all that certain about the time-line here.  It was a prolific issue and is really relatively common, so it's not too exceptional for one to have made it to Britain in the course of trade, or even been carried by one of Claudius' soldiers as a talisman - although it wasn't impossible for denarii to stay in circulation for a century at that time, this seems to have enough detail to be fairly bold even under encrustation - ie: it doesn't exhibit anything like the wear one would expect for a coin which had circulated for 100 years.

Here's an example showing all the details clearly http://www.stoa.org/gallery/album434/MK_15_04

Mark

18.71mm, 1.05g

1592-5 Elizabeth 1st hammered silver shilling (12 pence) Tun mintmark - sixth issue

31.61mm dia

1247 Henry III hammered silver voided penny

Rev HEN/RIO/NLV/VND Henri of London mint

1509-26 Henry VIII hammered silver half penny Portcullis Crowned mint mark - 1st issue

Obv HENRIC DI GRA REX AGL

Rev CIVI/TAS/LON/DON - London mint

1728 Portuguese Joao V milled gold - 1/2 Escudo (800 Reis) 0.9170 Gold

John V of Portugal

1485 Henry VII hammered silver farthing - double arched crown

Obv CIVI/TAS/EBO /RACI -York mint

A cast copper alloy mount dating to the seventeenth century AD.

Chronology

Broad period: POST MEDIEVAL
Period from: POST MEDIEVAL

Date from: Post AD 1600
Date to: Ante AD 1700