Luxembourg’s “Kalktuffquelle” in winter

In periods of extremely cold weather, something beautiful happens in Luxembourg…

It has been cold recently in Luxembourg, like, really cold. I’m talking way down into negative double figures. Take our garden pond, for example. Poor fish.

But when the weather gets this cold, something beautiful happens in Luxembourg: a “tufa” spring in the Mullerthal goes all, well… frozen.

We put on as many layers as we possibly could and ventured into the forest to check out this bizarre winter phenomenon:

From our parking spot, a raised wooden trail leading to the spring serves the dual purpose of preserving the forest floor from erosion and delighting any children off on an adventure. Down this fairy-tale path, it’s only a few hundred metres to the “Kalktuffquelle”… and it truly is a sight to behold:



How was this frozen fantasy created? Although it may look like Queen Elsa has paid a visit to Luxembourg, there is, of course, a more scientific rationale. You see, immediately above this “waterfall”, calcium-rich water rises up from the ground. Upon making contact with the air, this water loses some of its carbon dioxide, making it more alkaline (plants and algae living in the water also get rid of carbon dioxide through photosynthesis). This abrupt loss of acidity means that the calcium carbonate in the water can no longer remain in soluble form; it turns into a sediment, creating those weird shapes of soft, puffy tufa. And since the spring is on the side of a valley, the water tumbles softly down through this porous landscape to a glittering turquoise pool below.


When it remains extremely cold for several days on end, this constant dripping of water turns into magnificent ice columns, and the splashing of the drops in the pool below creates curiously-shaped formations, crystals and textures of ice.


This phenomenon doesn’t happen very often, so make sure you don’t miss it if you’re in Luxembourg during the next big freeze.

Where to find the Kalktuffquelle:

It’s in the east of Luxembourg, just off the road “CR 121” (Junglinster to Grundhof), roughly half-way between the hamlets of Blumenthal and Mullerthal. Parking available nearby (see map).

By foot, it is directly on the hiking trail “Mullerthal Trail 3“.

(Map sources:



Daisy the bus visited the Kalktuffquelle in March 2018. Winter tyres are a wonderful thing.

(c) 2018 Jonathan Orr




Author: daisythebus

Family travel bloggers based in Luxembourg. We write about "off the beaten track" travel adventures with our four children. Expect to read about nature, outdoor activities, culture and alternative ways of discovering the world around us.

36 thoughts on “Luxembourg’s “Kalktuffquelle” in winter”

  1. This is so beautiful! I don’t imagine it happens every year so I’m guessing you were really lucky to see it. Good to have something to be grateful for when it’s freezing cold! Thanks for sharing on #FarawayFiles

  2. Man and I thought we’d had it cold! Being all land locked and everything, I had visions of Luxembourg being all cosily tucked in then 😉 These things are AMAZING! I’ve pinned just in case I find myseld booking a flight to Luxembourg next winter instead of the Maldives!! #farawayflies

  3. Amazing! Saved and pinned your post. We plan to visit in the summer, so we will miss the ice formations, but it sounds like the hiking is another reason to visit!

    1. Yes, the hiking is amazing here. The Kalktuffquelle is also a nice spot even when it is not frozen, so maybe you’ll pass by it when out hiking in the Grand-Duchy. Give me a shout if you’d like any tips or advice; I’d be happy to help.

  4. Another magical Daisy the Bus adventure! The Northern Lights of Luxembourg, ha ha, I love it! I’m definitely sharing this neat and rare phenomenon with my boys, who love all things science! #farawayfiles

  5. Omg this is awesome!!! Reminds me of a similar waterfall I discovered when I lived in Montana that froze over during the winter! People would spray paint on it though, but still made it pretty! Pinned! #FarawayFiles

    1. Waterfall graffiti????? Now that’s a first for me. Although I do hope the idea doesn’t catch on in Luxembourg; I think I prefer this in its natural form 🙂

  6. Luxembourg has been on our bucket list for years – we were meant to go last year but my partner threw his back out a few days before the trip and we had to cancel. I have never seen such a beautiful sight – I love snow and frozen water and it’s just magical. Just popping over from #Countrykids

    Laura x

    1. It was indeed a rather beautiful sight, one of many in Luxembourg. Hope your husband’s back holds up and that you make it here in the near future!

  7. Wow that looks absolutely incredible! And to capture it on camera too, you did amazing with those photos. What a fantastic phenomenon to experience. #CountryKids

  8. I’ve had my eye on this post since spotting your Instagram pic the other day. What a sight!!! This is simply extraordinary, how I would love to witness it! Thank you for the lovely video, and for the science lesson too. I’d vaguely heard of tufa before (in Moorish architecture, I think, or is it a different word entirely?), but I didn’t know about the natural phenomenon.
    I shall share this on my Facebook page 😉

    1. Thank you for the lovely comments. It is indeed extraordinary – and was very short-lived. 48 hours after our visit, and despite the temperatures only barely scraping above zero, it was gone. I wonder if it will reappear next winter? And I’m afraid I don’t know much (anything?) about Moorish architecture 😀 but since tufa is effectively just a form of limestone, it is entirely possible that certain buildings may be made of certain forms of it. Something to research! 😉

  9. Stunning photos, what a beautiful phenomenon. Luxembourg has so much more going for it than I realised, and a science lesson too. Great post, love the colour of the water and those giant icicles #CountryKids

  10. Has it thawed up a little there yet? What a glorious sight – and a fun, hands-on learning opportunity, too. I envy your frozen rivers. I think it’ll be a while yet before the Thames is solid enough for Londoners to dig out their skates! Thanks for linking up with #CulturedKids

    1. Yes! I passed by today and it had almost completely disappeared (much to the annoyance of quite a few tourists and locals who had made the trip to witness it). I wonder when we’ll be able to see it like that again?

  11. What a fab science lesson. It’s oh so pretty and very lucky to get to see it. I think everyone should has been hit by the very cold this past few weeks!! #countrykids

  12. What a beautiful sight to see, I bet it feels almost magical when you’re watching the water drip down these unusual shapes. I can see why you made the effort to get out and see this beautiful occurrence, especially if it doesn’t happen regularly. I don’t think any of the waterfalls in Cornwall get so cold that occurrences such as the Kalktuffquelle happen, I’ll definitely make a note that should I ever be in Luxembourg during the icy conditions I’ll check it out!

    Thanks for sharing with me on #CountryKids.

  13. oh wow! It looks beautiful!! I love the colours too – winter always feels so washed out and pale (but good) – love how it brings some brightness to the area, but you can still tell it’s wintry. #countrykids

    1. It’s not guaranteed. It happened last winter too, but definitely does not occur every year. It wasn’t like this five days ago, despite the prior week or two being rather chilly (only rarely above freezing). It was only when the maximum daytime temperatures got nowhere near freezing for three or four days in a row that it started to take its current form. Basically, it is not an easy thing to plan to see… Luxembourg’s Northern Lights? 😀

    1. And only 10 minutes from our home. It makes you wonder how many other hidden gems are out there, secrets waiting to be unlocked with a bit of background knowledge.

      Thanks for your kind comment and greetings from (still freezing) Luxembourg!

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