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Hello,

can you tell me how old this Lamp is?
I found it in Bavaria, Germany.

Would it be March of the year ending in 9 during an odd decade?  Also, what factory symbol does it have?

The symbol most likely indicates the German Philips Aachen plant. 9C in this case for this lamp stands for March 1979 (March 1999 can be ruled out since this lamp was not in production at that time and March 1959 too since it by far predates this date code system)...

The owner noted to me that the etch is worn and the first digit may be a 2, so it's probably March 1972.  The other possibility would be March of 1992, if they were still in production at that time.

@Lampwizard, do you know when these lamps were discontinued?

This particular "Mushroom" shaped lamp made it least until 1998 when checking the most recent Philips Light Pocket catalogue that I have. So it has been discontinued between then and now.

This lamp could have been made 1999 but Philips at that time already did away completely with this stylish handwritten-like  "De Luxe" text which was more common for Philips lamps from the late 60s/early 70s.

Some trivia: the name originally was "Argenta Super Lux" and "Argenta K" (krypton filled for increased luminous efficacy) but in the 1993/1994 catalogue it was renamed to "Softone K" and "Super Lux" and in 1997/1998 to "Classictone Superlux" and Classictone Argenta K"...