elektron

Japanese: ēlektron（英語表記）elektron

…Banknote issuance system [Hidenari Yoshizawa]
[History of Currency]

[Ancient Greece and Rome]
Greek coins were not only the first in Europe, but also world-renowned for their artistic value. Because silver was produced in large quantities in Greece, silver coins were the main currency, with copper coins as secondary currency. Gold coins were used almost exclusively from the Orient (Lydia, especially Persia), and minting was the exception; elektron (a natural alloy of gold and silver, not found on the mainland) coins were only made in Ionia. The units of currency used were the drachma and the stater. …

From Amber

… [Akira Machida]
[Tradition]
Around 600 B.C., Thales discovered that amber is easily electrically charged. Amber is called electron in Greek, and it goes without saying that this is the origin of the word electricity. The ancient Chinese believed that when a tiger died, its essence entered the earth and transformed into amber.

*Some of the terminology that mentions "ēlektron" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…紙幣発券制度【吉沢英成】
【貨幣の歴史】

［古代ギリシア･ローマ］
　ギリシア貨幣はヨーロッパにおける最初のものであるばかりでなく，その美術的価値において世界に誇るべきものである。銀はギリシアにかなり産出するから，銀貨を主とし銅貨を補助貨とし，金貨はもっぱらオリエントのもの(リュディア，ことにペルシア)が使われ，鋳造されたことは例外的であり，エレクトロンēlektron(金と銀との自然合金で，本土には産しない)貨幣はイオニアで造られたのみである。貨幣の単位はドラクマdrachmaとスタテルstatērが使われた。…