Anandakanda 2.1.98

2.1.98

tāmravarṇamayo vāpi tāvacchudhyati mākṣikam /
<tṛtīyaḥ prakāraḥ>
agastipuṣpaniryāsaiḥ śigrumūlaṃ nigharṣayet //

or turns the color of copper; until that happens, mākṣika is purified.
<The third method>
One should rub śigru root with the juice of agasti flowers,