1971 - Lanka

Ten Cents - TRIAL

A set of TRIAL patterns were struck with date 1971 to select a cheaper alloy for the Five cents and Ten cents coins in which the Nickel-Brass metal had become almost half the face-value. Patterns were struck for both Five cents and Ten cents denominations in Nickel-Brass clad steel, Chromized steel and Aluminum with word TRIAL in raised letters on Obverse. Rare 1975 Aluminum off-metal-strikes (OMS) also exist for both Five cents and Ten cents. Aluminum was adopted and made legal for the Five and Ten cents coins from the 1978 issue. Aluminum had been used for the one and two cents coins since 1963.

SPECIFICATIONS
DenominationTen cents
AlloyNickel-Brass clad Steel
Diameter23.11/20.96 mm
Thickness1.55 mm
Weight4.04 gms
Shapeeight scallops
EdgePlain Steel
Die-Axis
1971_Lanka_10c_clad_trial_obverse 1971_Lanka_10c_clad_trial_reverse
KM unlisted
DenominationTen cents
AlloyChromized Steel
Diameter23.11/20.96 mm
Thickness1.41 mm
Weight3.69 gms
Shapeeight scallops
EdgePlain
Die-Axis
1971_Lanka_10c_steel_trial_obverse 1971_Lanka_10c_steel_trial_reverse
KM Unlisted
DenominationTen cents
AlloyAluminum
Diameter23.11/20.96 mm
Thickness1.55 mm
Weight1.30 gms
Shapeeight scallops
EdgePlain
Die-Axis
1971_Lanka_10c_al_trial_obverse 1971_Lanka_10c_al_trial_reverse
KM unlisted

Obverse : The Armorial Ensign of Ceylon, with word TRIAL to the right and upper side (2 O'Clock) along the periphery.

Reverse : The large numeral 10 with the value TEN CENTS in Sinhala, Tamil and English below and year of issue at the bottom within a circle of the traditional Sinhala Liyavela art with Lanka in Sinhala on top.

Considering the weight, thickness and edge of the coins it appears that the Steel core of the Nickel-Brass Clad pattern is similer to the Chromized Steel pattern.

Qualitative x-ray floresence spectra show the clear presence of Chromium with the Iron in the Chromized Steel TRIAL. NO trace of Chromium was detected on exposed Steel core along the edge of the Nickel-Brass Clad TRIAL. No Iron was detected on surface of same coin indicating a thick clad of Nickel-Brass.

I have seen 2+5/6 sets of these TRIAL coins. I am seeking information about other sets of these Pattern. I am not sure how many were produced or known to exist. Retired officer T. M. U. Sallay of the Central Bank of Ceylon, confirmed them to be official Patterns.

There is also a 1965 Ten Cents with word TRIAL in raised letters on both Reverse (10 O'clock) and on Obverse (9 O'clock). It is non-magnetic and of the same weight and metal as the standard issue of that year. It was struck most probably in Birmingham Mint when they got the subcontract from the British Royal Mint (BRM) which first struck it few years previously in 1963.

The TRIAL coins were scanned at 600dpi and the images are displayed at 250dpi. There appears to be slight corrosion on the obverse of Aluminum specimen imaged due probably to poor storage.