About us

Jakob Hoyer is the Danish man on the ground in Tanzania. He has been sourcing minerals for the most of his grown up life and has a considerable knowledge on the field.

Living in Tanzania for more than 12 years with his Tanzanian wife and their three children, he also knows the local culture, speaks Swahili and is motivated by seeing the local people taken part of his activities.

They live in Arusha on the slopes of Kilimanjaro, close to where Tanzanite is mined. Arusha is well-known, as the center of gem trade in Tanzania.

Jakob has had the passion for stones and minerals since he was a little boy collecting Neolithic tools and fossils with his parents in Denmark.

His first real mineral adventure lays more than twenty years back, when he explored the Illimausaq complex for Tugtupite and other gemstones.

Recently Asha, the wife of Jakob, formed Opengemstones Co Ltd in Tanzania, and their adventure for Minerals in Tanzania started.

The office is located in Arusha, and through Asha, they own and sponsor several mines together with local shareholders.

The project started in 2017, when some major sized quartz of unseen quality was unearthed, and Opengemstones Co was offered some large Crystals from this location.

The world was to discover the amazingly clear and large size quartz Crystals from this new find.

Now Mondo Quartz is internationally recognized as one of the finest optical quartz in the world.

The founders of MondoCrystals ApS in Denmark are Henrik Tranum and Rene Andersen. Henrik Tranum is the brother in law of Jakob (Opengemstones Ltd., Arusha).

After visiting Jakob several times in both Zanzibar and Tanzania, the interest of stones and gems has increased. In 2018, they made an agreement with Jakob in order to make a co-operation between the Mondo mines and their company in Denmark.

This gives a unique opportunity of sourcing high quality ethically sourced Crystals and Gemstones and distribute through MondoCrystals.

The purpose of Mondo Quartz in Denmark is to supply crystals and minerals mainly from the Mondo mines in Tanzania and directly to the end users or retailers in Denmark and internationally.

This was an opportunity not to be missed, and MondoCrystals became reality in September 2019.

We can source any type of mineral for you, directly from the mines in Tanzania.