AN SMA PLT MISTOOK A BLACK TOP PORTION OF THE RWY AS NOT BEING PART OF THE RWY.

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ON TAXI OUT FOR TKOF; I FOLLOWED A TWIN TO RWY 4. ON THE WAY OUT; I NOTICED THE TXWYS AND RAMP AREA CONTAINED A LOT OF LOOSE STONES. AS I APCHED RWY 4; I NOTICED IT CONSISTED OF A CONCRETE CTR SECTION AT LEAST 100 FT WIDE RUNNING THE LENGTH OF THE RWY (4000 FT) WITH ONE APPROX 25+ FT WIDE STRIP OF BLACK MACADAM RUNNING THE LENGTH OF THE RWY ON EITHER SIDE OF THE CONCRETE SECTION. I FOLLOWED THE LIGHT TWIN AHEAD (WHO BEGAN HIS TKOF ROLL) ONTO THE BLACK SECTION (AFTER DULY CHKING THE FINAL) TO PERFORM A 'STONE-FREE' ENG RUN-UP; IE; I WAS CONCERNED ABOUT PICKING UP STONES IN THE PROP. TWIN ANNOUNCED HIS INTENTION TO REMAIN IN CLOSED TFC AND ASKED ABOUT ACFT ON THE RWY (ME) WHAT MY INTENTIONS WERE AND I REPLIED; 'TO COMPLETE MY RUN-UP AND I'LL BE GONE AND THAT IF YOU NEED MORE ROOM; I'LL BE WILLING TO GIVE YOU SOME.' HE DECIDED TO GO AROUND! I THEN LOOKED AT THE RWY CONDITION AND NOTICED THE LIGHTS WERE AT THE VERY EDGE AND OUTBOARD OF THE BLACK MACADAM SECTION; AND WITH ITS CONTRAST WITH THE WHITE CONCRETE SECTION; APPEARED MUCH THE SAME AS A GRASS STRIP ADJACENT TO AND PARALLEL TO A LOT OF RWYS BEFORE REACHING THE LIGHTS. I REALIZED THAT IN MY CONCERN TO RUN-UP ON A CLEAN SURFACE; THAT I ACTUALLY HAD CONDUCTED IT ON THE RWY. I MISTOOK THE BLACK MACADAM STRIP AS NOT BEING PART OF THE RWY ITSELF; WHICH I REALIZED IT WAS. DEFINITELY A MISINTERP ON MY PART; WHICH HOPEFULLY CAN BE EXCUSED BECAUSE OF MY UNFAMILIARITY WITH THE ARPT. I REALIZE IT'S A MATTER OF MONEY; BUT A MACADAM RESURFACING OF THE WHOLE RWY IS IN ORDER HERE -- UNTIL THEN; I'LL HAVE TO BE A LOT MORE VIGILANT!