Black Basalt Rock Dust (High Calcium & Magnesium) NEW!

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12 reviews

Size: 1kg
Sale price$7.00 Regular price$14.00

Pickup available at Bellambi

Usually ready in 24 hours


Black Basalt Rock Dust was formed millions of years ago when hot lava came into contact with large bodies of water. The resulting product is mineral dense and perfect for amending potting soils, lawns, fairways & for fruiting/flowering plants.

  • Packed full of Silica, Calcium & Magnesium for powerful growth! It will help raise and sustain soil pH levels to unlock nutrients and allow for lusher, healthier plant growth!
  • Perfect for adding into Coco Coir for Calcium & Magnesium buffering! Even better on fruiting trees, lawns, and areas where high rainfall has occurred, resulting in acidic soils.
  • It will raise the pH of Peat Moss to an acceptable range for optimal growth.

Usage Guide

100g per m2 or incorporate at 5-10% with your existing fertilizer routine. Apply 50-80g per 30L of potting soil.

Apply at the start of each season for the best results.

Typical Analysis

pH 8.5, Silica 43%, Calcium 7%, Magnesium 14%, Potassium 1.7%, Iron 14%, Manganese 0.2%

Our Black Basalt rock dust is largely made up of the mineral olivine. It is a silicate mineral often found in basalt and peridotite, two volcanic rocks. Olivine is also found in meteorites. The most typical source of olivine rock dust is volcanic deposits. Huge scientific discoveries and leaps are currently being explored regarding this mineral rock dust and its unique ability to sequester carbon in much larger quantities than ever seen before!

Other benefits of using Black Basalt Rock Dust include

  • Improving soil fertility: Black Basalt Rock Dust is rich in essential plant nutrients, including magnesium, iron, and calcium, which can help to improve soil fertility and support healthy plant growth.
  • Balancing soil pH: Black Basalt Rock Dust can also help to balance soil pH levels, making it more suitable for a wider range of plants.
  • Improving soil structure: The fine powdery texture of black basalt rock dust can help to improve soil structure and increase the availability of water and air to plant roots, leading to healthier plant growth.
  • Providing trace minerals: Black basalt rock dust is also a source of trace minerals that are important for plant health and growth, including manganese, zinc, and copper.
  • Enhancing soil biota: The addition of black basalt rock dust to soil can also help to enhance the population of beneficial soil microorganisms, which play an important role in nutrient cycling and disease suppression.

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Customer Reviews

Based on 12 reviews
Avril Summers
Improving my potting soil

I needed to find specific amendments to
Make my own healthy potting mix. I found Dr Greenthumbs online who had most of my requirements. Response time was excellent even for those living in Tasmania. And my order arrived promptly and in good condition.
I am now armed with everything I need to create a healthy soil. Highly recommend this company

Trent Harvey
Great service

I just love these products

Thumbs up!

A while back I gave a review for some dry amendments and was saying that my organic gardening had grown to a new level. I could go further now to say, these dry additives have opened up a whole new world in my garden!

Glen Rae
Black Goodness

How’s the magic of this fine dust, a little goes a long way. Then in a short amount of time my plants gave a big thumbs up. Doesn’t take much money to see a big difference in outcome

Black Gold

Using it to balance the PH in my raised garden beds, as they kept dropping below 6. I've been able to get the PH back up to 6.5 using the Black Basalt Rock Dust.. Great stuff :)

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