De Zhong 德钟, TieSha ZhuNi 铁砂朱泥, 150ml, made by renowned family for TieSha ZhuNi, Artisan ZHU JIE 朱杰。

Tie Sha Zhu Ni 铁砂朱泥 is a Yuan Kuan type, i.e. unadulterated and original ZhuNi type.
It is not a type of mixed clay.  It is an adulterated ZhuNi material PICKED AT SITE.

Read on.
Usually,
1) Ore pickers will pick at site but avoid: ZhuNi ores that appear to have too obviously high IRON content,
2) and/or after picking, they will try to select out parts high in iron content to be omitted during the ore processing into bricks of clay and subsequently for pot making.

Such avoidance of working with ZhuNi with too high iron content is because, ZhuNi with too high iron content will be DIFFICULT to work with.

However, for Tie Sha Zhu Ni, only certain few families of Artisans in YiXing: they will specially AND purposely pick at site: ZhuNi ores that have obviously HIGH IRON content.,

AND these families of Artisans know how to work with and form up pots with them.

Zhu Jie is the Craftsman whom we trust and also, adept at crafting with Tie Sha Zhu Ni 铁砂朱泥。

Tie Sha Zhu Ni pots are treasured because they are amazing in steeping and brewing up Oolong teas, High Fragrance teas and Dark Pu-Er tea types.

You can see the high iron content by virtue of the multiple black dots as visible throughout the surfaces of this pot.

Very rare for one successful piece to come through perfectly.  Do cherish it!