efflorescent

Kobo Abeの小説 "The Woman in the Dunes" を読んでいます。

The surface of the moon was like a grainy, powder-covered scar...cheap, dried-out soap...a rusty aluminum lunchbox. Then as it came into focus, it assumed an unexpected form: a white skull--the universal symbol for poison...white, powdercovered tablets at the bottom of his insect bottle...an amazing resemblance between the texture of the moon's surface and that of the efflorescent tablets of potassium cyanide.

"efflorescent tablets" の "efflorescent" とは何でしょう？　辞書を見ます。

・Farlex Partner Medical Dictionary：Denoting a crystalline body that gradually changes to a powder by losing its water of crystallization on exposure to a dry atmosphere.
・Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health: becoming powdery by losing the water of crystallization.

何か専門的な言葉ですね。 多くの辞書は形容詞の "efflorescent" ではなく、covered with or forming an efflorescence（Collins Dictionary）とかthe process or product of efflorescing chemically (Merriam-Webster)と説明しているので "efflorescence" を見ます。 

・Oxford English Dictionary: (chemistry) the powder that appears on the surface of bricks, rocks, etc. when water evaporates
・Collins Dictionary: the changing of certain crystalline compounds to a whitish powder or powdery crust through loss of their water of crystallization 

英語では専門用語の様ですが、原文の日本語は何なのか気になります。