LAS VEGAS — Amazon, the company that defined the world of online commerce, is venturing further into the world of physical retail — experimenting with standalone, automated “Kindle Kiosk” vending machines in selected airports and shopping malls.

The machines sell everything from the $379 Kindle Fire HDX to a $20 Kindle PowerFast adapter, in addition to Kindle e-readers and covers.

Amazon’s stealthy experiment started rolling out in November, according to an Amazon customer service representative. We spotted one last night at the McCarran International Airport in Las Vegas — doing a double-take when we walked by. One airport worker said it was installed within the past day. That means it’s in place just in time for people traveling through the airport on the way home from CES.

We used it to purchase a Kindle power adapter. Ours was the machine’s second transaction, according to the numbering on our receipt.

The kiosk that we encountered appears to be identical to the ones that were included in temporary Amazon “pop-up stores” at a few U.S. shopping malls during the holidays, as reported by the Wall Street Journal in November. However, the company told the Digital Reader blog at the time that the stores weren’t really stores, but part of a Kindle’s ‘Read-It-To-Believe-It’ marketing campaign designed to promote the Kindle Paperwhite e-reader.

An Amazon spokesperson tells us via email that the company has made the kiosks available at a variety of locations, including events, malls and airports. “We’re very happy with the customer response so far, and are excited to give customers (like you!) another easy way to purchase accessories and also Kindle e-readers and Kindle Fire tablets,” the spokesperson said.

The experiment signals the company’s desire to expand beyond online sales and third-party retail stores, directly selling its hardware and accessories in physical locations. It’s also notable in the context of past predictions that Amazon might want to buy Coinstar and Redbox parent Outerwall, the automated vending machine company based in Bellevue. That was pure speculation, but such a move would significantly increase Amazon’s physical footprint.

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Tech companies such as Apple and Microsoft have ventured into physical retail with splashy stores, but it’s no surprise that Amazon — with its low margins and love for automation — would instead try a vending machine. It’s not clear how many people will feel comfortable purchasing something as expensive as a $379 tablet from a vending machine. But at $69, the standard Kindle e-reader could be an impulse buy for someone preparing for a long flight.

Amazon’s kiosk is powered by Zoom Systems, which makes similar automated retail machines for Best Buy and other big brands.

Our experience with the Kindle Kiosk at the Las Vegas airport wasn’t entirely smooth. At different times during the process of buying the Kindle power adapter, interface was unresponsive for 10 seconds or more. We were able to work through the sluggishness, and after completing the purchase with our credit card, the adapter slid neatly into the bin at the bottom of the machine. The on-screen dialog explained how the item could be returned using the company’s online system.

However, the kiosk didn’t allow us to link the purchase to an existing Amazon account, which would seem to be an obvious feature for Amazon to add in the future.

Here’s a collection of photos showing the kiosk and purchase process. Click any image to open a gallery.