when we think of climate action, we often picture solar panels, wind turbines, or electric cars. but at alt carbon, we work with something more ancient. more grounded. a rock.

basalt.

a dark volcanic stone — often overlooked — yet quietly powerful. when crushed and spread on soil, it reacts with rainwater and atmospheric CO₂, locking carbon away for thousands of years. It’s one of earth’s oldest climate tools, and we’re putting it back to work.

but before it captures carbon, it has to be found, crushed, quality-checked, paid for, transported, and weathered in the field. None of that happens in a lab. It happens under monsoon skies, on dusty roads, in real-time, with real people. This is where climate ambition meets Indian ground reality.

this is the story of basalt. and this is where it all begins.

sourcing basalt: the dusty reality

look at the picture below. what is your first thought? 

my first thought: if dune had a sequel, it could have been filmed here! 

the air was so thick with dust that I had to borrow my driver’s towel to protect myself from inhaling this dusty air.

my first field trip had just started. this is in early 2024. within minutes of stepping out of my car, I was surrounded. a few men. silent. suspicious. this wasn’t hostility—it was skepticism. who is this outsider? what does he want?

it reminded me that a seemingly simple task of buying basalt dust can quickly turn complex when you’re operating in India’s informal economies; where relationships, reputations, and rituals matter as much as regulations. 

from byproduct to breakthrough

basalt dust is usually a waste product. It’s leftovers from crushing boulders for roads and buildings. but what’s of little value to the construction industry is gold to us.

after visiting these crushers, I learnt a few things:

• presence matters: having someone physically at the crusher during loading is non-negotiable. visual checks and touch-based inspections can catch what paper specs miss. 

• speed matters: timely payments and clear communication keep operations smooth and trust intact. the latter is more important than the former. In fact, the latter dictates everything about the former — understanding these cultural nuances is key to doing business in India. 

• weather matters: rain may be a gift for enhanced weathering, but it’s a nightmare for sourcing. wet basalt weighs 20% more, and you’re paying for water if you’re not careful. wind? It can literally blow your carbon credits away.

after evaluating multiple crushers, we decided to source basalt from one located closer to our tea garden in west bengal. proximity to the site, the right price, and the quality of the basalt dust all played a role in the decision. logistics efficiency and the cost-effectiveness of transportation were crucial factors in making this choice, as they significantly impact overall project timelines.

transporting: a tribute to truckers

moving basalt is not glamorous. but it’s the lifeline of our work. It’s also the most underappreciated aspects of our work. it’s not just about moving rock dust. it’s about the hard work of truckers, who brave long journeys, weather changes, and difficult roads to deliver on time. a task that may seem simple on the surface—load, drive, and unload—demands respect for the complex networks that makes it possible.

just to paint a picture: 

8 trucks.
20 days.
1,200 metric tons of basalt dust.
over 350 kilometers.
all during monsoon.

rains came and went, turning roads into mud tracks and dust into sludge. yet, the trucks kept coming; carefully loaded, weighed, and dispatched.

behind every tonne of basalt we deploy is a network of workers, drivers, loaders, and logistics coordinators.

climate action may start with science, but it runs on people.

this is the first part of my field diaries, from rock to road. stay tuned for the next part, where I delve into the challenges and insights of applying basalt in the fields, and the meticulous process of soil sampling.

because in climate work, sourcing is just the beginning. the field is where the magic happens.