The theme is revealed at 26A: With 113-Across, 1972 song lyric hinting at this puzzle's theme: I'VE BEEN A MINER FOR A/ HEART OF GOLD, with theme tie-ins at 64D: Like 113-Across (BY NEIL YOUNG) and 68D: Atomic number of the special parts of this puzzle which, when connected, form a 113-Across (SEVENTY-NINE).
The buried treasure is found in ten squares:
33A: Scene (TABLEAU), crossing with 27D: Lover boy (BEAU).
36A: Victorians, e.g. (AUSSIES)...with 28D: Overseas Mrs. (FRAU).
39A: Outdoor shindigs (LUAUS)...with 34D: Letters from Greece (TAUS).
41A: "Your mother wears army boots!," e.g. (TAUNT)...with 35D: Mideast's House of __ (SAUD).
58A: "Homage to Clio" poet (AUDEN)...with 58D: Author who wrote "One half of the world cannot understand the pleasures of the other" (AUSTEN). An exceptional literary cross.
59A: Some shavers (BRAUNS)...with 54D: Extol (LAUD).
61A: Pianist Claudio (ARRAU)...with 62D: Independent examinations (AUDITS).
77A: Child-care provider (AU PAIR)...with 77D: Sound (AUDIO).
79A: Capital city about an hour by plane from Miami (NASSAU)...with 80D: Carpentry tool (AUGER).
97A: European air hub (DeGAULLE)...with 100D: Park Avenue, for one (AUTO).
This was just plain fun. Once you got the gist of this theme, you pretty much knew that buried treasure would be in the symmetrically opposite square...well, except for one. Those nine squares in the center were the absolute last to fall for me...for that very reason.
A puzzle like this has to have left/right symmetry, similar to Tyler Hinman's a couple of weeks ago. It made it a little harder for me to figure out which square was the opposite, symmetrically speaking, but that didn't diminish from the overall pleasantness of the puzzle.
Clever cluing all over the place...
6A: Strands in a diner (spaghetti). A gimme.
21A: One who keeps a beat? (patrolman).
25A: Just above average (C plus). These typically trip me up, but not today.
83A: Music unlikely to be played at a party (dirge).
106A: It's often "proud" (sponsor).
119A: Jalapeño feature (tilde).
3D: Tropical cave dwellers (fruit bats).
16D: Locked up (in prison).
70D: Kind of platter (pupu).
Several things were unknown to me. I got most of them from the crosses, but had to Google to confirm a letter when the crosses were equally unknown.
45A: Classic Atari game (Asteroids). Not something I ever played.
52A: "Typee" sequel (Omoo). Knew of Omoo, knew that Melville wrote it...just didn't know it was a sequel.
10D: Bill who created the comic strip "Smokey Stover" (Holman). Sorry, I've never heard of Bill Holman or his comic strip.
11D: Missy __ with the 2002 hit "Work It" (Elliott). Easy enough to guess that one, but I had no clue.
17D: Deep black garnets (melanites). Have never heard of them.
66D: 1954 Jean Simmons movie (Desiree).
There's so much more good stuff in this puzzle. How about commenting on one or two of your favorites.
Here's the grid. I'm happy that the heart of gold shows.
And I'm off to bed. See you tomorrow.