The　structure　and　granularity　of　biological　origin　aragonite　from　abalone　shell　during　wet　grinding　in　a　ball　mill　were　studied　with　X-ray　diffractometer,　with　morphology　studied　by　scanning　electron　microscope　(SEM).　It　is　shown　from　the　results　that　the　particle　sizes　of　aragonite　decreased　with　grinding　time,　so　did　the　X-ray　diffraction　(XRD)　peak　intensities,　while　the　full　widths　at　half　maximum　increased.　A　calcite　XRD　peak　with　low　intensity　and　great　width　was　observed　in　nearly　all　the　samples　with　various　grinding　time,　whereas　the　intensity　of　the　peak　increased　obviously　after　grinding　time　300　min.　It　is　shown　from　the　SEM　results　that　the　size　of　aragonite　dropped　with　grinding　time　until　it　reached　20　nm　and　then　kept　constant,　while　that　of　calcite　dropped　first　and　then　rose　at　the　minimum　about　10　nm　until　to　the　constant　size　as　in　aragonite.　It　was　observed　that　the　mineral　content　obtained　from　XRD　show　an　obviously　change　that　the　calcite　increases　while　aragonite　decreases,　which　indicated　the　occurring　of　a　polymorphic　transformation　of　aragonite　into　calcite.