Bamidbor 17 (17) records the instruction to take a staff for each of the chieftains.
דַּבֵּ֣ר ׀ אֶל־בְּנֵ֣י יִשְׂרָאֵ֗ל וְקַ֣ח מֵֽאִתָּ֡ם מַטֶּ֣ה מַטֶּה֩ לְבֵ֨ית אָ֜ב מֵאֵ֤ת כָּל־נְשִֽׂיאֵהֶם֙ לְבֵ֣ית אֲבֹתָ֔ם שְׁנֵ֥ים עָשָׂ֖ר מַטּ֑וֹת אִ֣ישׁ אֶת־שְׁמ֔וֹ תִּכְתֹּ֖ב עַל־מַטֵּֽהוּ׃
Speak to the Israelite people and take from them—from the chieftains of their ancestral houses—one staff for each chieftain of an ancestral house: twelve staffs in all. Inscribe each man’s name on his staff,
One might have thought that in order to have a fair test, these staffs should have been made from the same material.
Of what material(s) were the staffs made?
Note: Jewish Encyclopedia contains the following - Midrash Yelamdenu (Yalḳ. on Ps. ex. § 869)
"It was made of sapphire, weighed forty seahs (a seah = 10.70 pounds)…
but I do not know how authoritative this is.