Can Aluminum vessels be Mekabel Tumah? (Obviously) it's not written in Chumash, so is it like iron (which can) or like glass (which can't)
Rav Danny Wolf of Yeshiva Har Etzion has a shiur on whether Kohanim can take an aeroplane that flies above cemeteries. Integral to this question is whether aluminium can be mekabel tumah.
The Torah (במדבר ל"א, כב) lists only six metals. So the question is whether the Torah's list is exclusive or just gives examples of metals. The Mishnah and Gemoro give no guidance on this but the author finds help in the discussion of whether glass can be mekabel tumah. Rashi on Rosh Hashono 19b on the words וחכמים מטהרין says:
...טומאת כלי זכוכית דרבנן, שאין כלי מתכות טמאין דאורייתא אלא המנויין בפרשה: הזהב והכסף והנחשת והברזל וכו
The tumah of glass vessels is Rabbinic because only the six listed metals are mekabel tumah. The Vilna Gaon agrees with Rashi.
The Rambam on the other hand includes as mekabel tumah any material that can be melted but excludes glass which is not one of the materials which are melted (!).
So it seems that the issue is a machlokes in the earlier sources.
In our time, Reb Moshe Feinstein (איגרות משה יורה דעה ח"ג סימן כב) agrees with Rashi and excludes aluminium from Biblical tumah.