Gemara

(Mishnah): The Chashmona'im buried the rocks of the Mizbe'ach (that the Yevanim had used for idolatry) under a chamber in the Mikdash.

Question: Why was Genizah required? They could have forced Nochrim to break (and be Mevatel) the rocks!

Answer: We must build the Mizbe'ach with "Avanim Shelemos" (complete rocks).

Question: They could smooth them out later (with a blade)!

Answer: This disqualifies rocks for the Mizbe'ach - "Lo Sanif Aleihem Barzel."

Zevachim 54a (Rav): The Yesod (base of the Mizbe'ach) did not physically extend to the southeast corner.

Question (Beraisa): To build the Mizbe'ach, we bring a frame 32 Amos square and one Amah tall; and whole, smooth stones (big and small), plaster, molten lead and pitch; mix them and pour it into the frame (this forms the Yesod).

Suggestion: Perhaps after making a square Yesod, we cut off (all but one Amah of) the southern and eastern sides.

Rejection: The Torah requires "Avanim Shelemos"!

Chulin 18a (Rav Huna bar Rav Ketina): If the Mizbe'ach was dented b'Chagiras Tziporen (enough for a fingernail to get caught while scraping it along the surface), it is Pasul.

Sukah 48b: A case occurred in which a Tzeduki poured Nisuch ha'Mayim on his feet, and everyone threw their Esrogim at him. The Keren (protrusion at the top of the corner of the Mizbe'ach) was dented. They sealed it with salt so that the Mizbe'ach would not appear dented. However, a Mizbe'ach missing a (valid) Keren is Pasul.

Tamid 26b (Mishnah): Stone "Rovdim" (ledges) jutted out around Beis ha'Mokad (a chamber in the wall around the Azarah)

Question: We may not cut stones to make ledges -- "veha'Bayis b'Hibanoso Even Shelemah"!

Answer (Abaye): They cut the stones to the proper sizes (to make ledges) outside the Azarah -- "Avnei Eser Amos v'Avnei Shemoneh Amos."

Midos 36a (Mishnah): Stones for the ramp and Mizbe'ach were brought from the valley of Beis Kerem. They would dig land that had never been dug, and bring whole stones that never touched iron. If an iron instrument touched a rock, or if a rock was chipped through any means, it was Pasul.

If a rock was chipped, it was Pasul. The rest were valid.

We whiten (plaster over) the ramp and Mizbe'ach twice a year, (before) Pesach and Sukos. We whiten the Heichal (before) Pesach. We do not whiten with an (iron) builder's trowel (rather, with a wooden one), lest it touch the stones and disqualify them. Iron was created (with potential) to shorten life; the Mizbe'ach extends life. It is not proper that what shortens (life) touch what extends.

Sotah 48b (Beraisa - R. Yehudah): Shlomo used the Shamir (a special worm that can pierce anything hard) to build the Mikdash. We understand "it was built with whole rocks, like they were quarried" simply;

R. Nechemyah: You cannot say so! It says "these rocks... cut by a saw"!

Question: It says "a saw was not heard in the Mikdash during the building"!

Answer: They cut the rocks outside, and brought them in.

Rebbi says, I hold like R. Yehudah regarding the rocks of the Mikdash, and like R. Nechemyah regarding the rocks used to build Shlomo's house.

Rishonim

Rambam (Hilchos Beis ha'Bechirah 1:8): We build the Heichal and Azarah with big rocks. If they did not find big rocks, they use bricks.

Kesef Mishneh: The Mechilta expounds "if you will build a stone Mizbe'ach" to teach that you may make it from rocks, or from bricks.

Rambam (ibid.): We do not split or cut the rocks in Har ha'Bayis. We do so outside, and then bring them in for the building. It says "big rocks, precious rocks to found the Bayis, hewn rocks", and it says "a saw was not heard in the Mikdash during the building"!

Question: Since Rebbi rules like R. Yehudah regarding the rocks of the Mikdash, why does the Rambam rule like R. Nechemyah?

Answer #1 (Ri Korkus): The verses support R. Nechemyah. Rebbi's opinion is not a Hachra'ah (an intermediate opinion, which we always follow) because R. Nechemyah did not discuss rocks of Shlomo's house.

Answer #2 (Kesef Mishneh): A Hachra'ah Shelishis (it distinguishes based on a factor that the previous opinions did not even suggest that it could change the law) is not a Hachra'ah. Also, the Stam Mechilta, the verses, and the Gemara in Tamid are all like R. Nechemyah.

Rambam (14): If a rock was dented b'Chagiras Tziporen, like the way we test slaughter knives, it is Pasul for the ramp or the Mizbe'ach. We require "Shalem rocks." We dig until reaching a place that it is evident that it was never worked or built on, and take rocks for the Mizbe'ach from there, or from the great (Mediterranean) Sea. Also rocks for the Heichal and Azaros were Shalem.

Kesef Mishneh: The Rambam holds that rocks for the Heichal and Azaros were Shalem, i.e. totally smooth. However, they would cut them and smooth them outside using iron, like we said above. However, iron could not be used for the Mizbe'ach. In Tamid it says that they cut the rocks for the ledges around Beis ha'Mokad. The Mechilta expounds "Lo Sivneh Eshen Gazis" - cut rocks are Pasul for the Mizbe'ach, but not for the Heichal and Kodesh ha'Kodoshim. The Rambam says that iron disqualifies only regarding the Mizbe'ach (Halachah 15), because the Mizbe'ach was made to lengthen life

Lechem Shamayim (Ya'avetz, brought in Likutim in Frankel Rambam): Even for the Heichal and Azarah, for which iron does not disqualify, R. Yehudah requires that the rocks are Shalem from when they were quarried. R. Nechemyah requires Shalem from when they were built into the Mizbe'ach. Rocks need not be totally smooth, even for the Mizbe'ach. Even if there are depressions, if there is no catch for a fingernail to get caught in, it is Kosher.

Rambam (15): Rocks of the Heichal or Azarah that were dented or cleaved are Pasul. We do not redeem them; we bury them. If iron touched a rock, even if it was not dented, it is Pasul for the Mizbe'ach or ramp -- "Ki Charbecha Henafta Aleha va'Techalelha." If a rock touched iron, one who builds it into the Mizbe'ach or ramp is lashed due to "Lo Sivneh Eshen Gazis". One who builds a dented rock transgressed an Aseh.

Kesef Mishneh: The Aseh is "Avanim Shleimos Tivneh Es Mizbach Hash-m." Midos 3:4 equates the ramp to the Mizbe'ach.

Question (Tosfos Sukah 49a DH she'Kol): Why did the Gemara need to say that a Mizbe'ach missing a Keren is Pasul? Even if it was not dented, since part of the rock was missing, it was not "Avanim Shleimos", like it says in Zevachim!

Answer (Tosfos): In Zevachim, the Gemara means that if we will cut off the corner, it will be dented, and this is not Avanim Shleimos (smooth). One cannot smooth it with a knife, due to "Lo Sanif Aleihem Barzel."